Kahalalide F and Related Compounds

ABSTRACT

A process is provided for preparing kahalalide F and which leads to other kahalalide mimic compounds having useful biological activity.

KAHALALIDE F AND RELATED COMPOUNDS

This application claims priority as a continuation under 35 U.S.C. 120 from U.S. Ser. No. 10/182,881, filed Jun. 3, 2003, as entry of the national phase of PCT/GB01/000576, filed Feb. 9, 2001, claiming priority under 35 U.S.C. 119(a)-(d) from UK 0002952, filed Feb. 9, 2000. The contents of each of the above-listed applications are incorporated by reference.

The present invention relates to kahalalide compounds, and in particular to kahalalide F and related compounds, as well as a synthetic route for such compounds.

BACKGROUND OF THE INVENTION

Kahalalide F is a bioactive cyclic depsipeptide isolated from the sarcoglossan mollusc Elysia rufescens and its diet, the green alga Bryopsis sp. Kahalalide F was first isolated by Hamann and Scheuer, see Hamann, M. T.; Scheuer, P. J. J. Am. Chem. Soc. 1993, 115, 5825-5826. In this publication, the absolute stereochemistry of individual valines (3 D-Val and 2 L-Val) and of threonines (L-Thr and D-allo-Thr) was not determined. In a later publication, Scheuer et al. (Goetz, G.; Yoshida, W. Y.; Scheuer, P. J. Tetrahedron 1999, 55, 7739-7746) assigned a position in the molecule for the 5 Val and the 2 Thr.

Thus, the structure for Kahalalide F according to Scheuer et al. was:

In the meantime, Prof. Reinhart also assigned the individual position of the 5-Val and the 2-Thr (K. L. Rinehart, personal communication). While for the 2 Thr and 3 Val, his assignation concords with that of Prof. Scheuer, for the last 2 Val there is a discrepancy. Thus, in the Rinehart assignment, the two consecutive Val in the side chain are switched and the structure is of the formula (I):

It is now accepted, and demonstrated again in this text, that the correct formula for kahalalide F is the formula (I).

The structure is complex, comprising six amino acids as a cyclic part, and an exocyclic chain of seven amino acids with a terminal acyl group. Kahalalide F (I) is an exceedingly potent and rare marine-derived antitumour agent, though the absence of adequate quantities has slowed plans for clinical trials.

Other kahalalide compounds are known, and for example we refer to Hamann, M. T., et al., J. Org. Chem., 1996, “Kahalalides: Bioactive Peptides from Marine Mollusk Elysia rufescens and its Algal Diet Bryopsis sp.”, vol. 61, pp. 6594-6660. As well as kahalalide F, this article gives structures for kahalalides A to E. Kahalalide K was reported in J Nat. Prod. 1999, 62, 1169, and kahalalide O was reported in J Nat Prod 2000, 63, 152.

The structures for these further kahalalide compounds are shown in the following formulae:

The cyclic kahalalides have a ring of amino acids, and a side chain which terminates in an acyl group.

Kahalalides have a range of biological activities, notably antitumour and antituberculosis activity.

SUMMARY OF THE INVENTION

The present invention provides mimics of natural kahalalides. The compounds may differ in one or more amino acids, and one or more components of the acyl side chain.

Suitably the mimics of this invention have at least one of the following features to differentiate from a parent naturally occurring kahalalide:

1 to 7, especially 1 to 3, more especially 1 or 2, most especially 1, amino acid which is not the same as an amino acid the parent compound;

1 to 10, especially 1 to 6, more especially 1 to 3, most especially 1 or 2, additional methylene groups in the side chain acyl group of the parent compound;

1 to 10, especially 1 to 6, more especially 1 to 3, most especially 1 or 2, methylene groups omitted from the side chain acyl group of the parent compound;

1 to 6, especially 1 to 3, more especially 1 or 3, substituents added to or omitted from the side chain acyl group of the parent compound.

For cyclic kahalalides, the amino acid addition or omission can be in the cyclic ring or in the side chain.

Examples of this invention are compounds related to kahalalide F, and having the formula:

wherein Aaa₁, Aaa₂, Aaa₃, Aaa₄, Aaa₆, and Aaa₇ are independently α-amino acids of L or D configuration, if applies; wherein R₁, R₂, R₃, R₄, R₅, R₆, R₇ are each independently H or an organic group selected from the group consisting of an alkyl group, an aryl group, an aralkyl group, and their substituted derivatives with an hydroxy group, a mercapto group, an amino group, a guanidino group, a halogen group; wherein X₁ is independently O, S, or N; wherein R₂ is, if applies, independently H or an organic group selected from the group consisting of an alkyl group and an aralkyl group; wherein Aaa₅ is independently an amino acid of L or D configuration, if applies; wherein X₂ is independently an organic group selected from the group consisting of an alkenyl, an alkyl group, an aryl group, an aralkyl group, and their substituted derivatives with an hydroxy group, a mercapto independently H or an organic group selected from the group consisting of an alkyl group, an aryl group, an aralkyl group, and their substituted derivatives with an hydroxy group, a mercapto group, an amino group, a guanidino group, a halogen group; wherein R₈ is independently of the following formulae III, IV, or V:

wherein R₉, R₁₀, and R₁₁ are each independently H or an organic group selected from the group consisting of an alkyl group, an aryl group, an aralkyl group, and their substituted derivatives with an hydroxy group, a mercapto group, an amino group, a guanidino group, a carboxyl group, a carboxamido group, a halogen group; R₉ and R₁₀ can form part of the same cycle; R₉ can confer S or R configuration, if applies, to the carbon attached to; and n is 0 to 6. The definitions of the amino acids can also be varied to allow for proline and analogous amino acids including hydroxyproline. The formulae (III), (IV) and M can be intermixed to give a side chain made up of repeat units in more than one of these formulae.

In a modification, one or more of the ring amino acids Aaa-6 and Aaa-5 of the hexamino acid cycle is omitted or an amino acid Aaa-7 is added between Aaa-6 and Aaa-1, in order to arrive at rings having four, five or seven ring amino acids. Six ring amino acids is preferred.

The present invention is further directed to a synthetic process for the formation of Kahalalide F compounds and related structures.

PREFERRED EMBODIMENTS

Preferred compounds are related to Kahalalide F (I), wherein in the formula (II), Aaa-1 is D-allo-Thr (X₁=O, R₁=CH₃), Aaa-2 is D-allo-Ile (R₃=1-methylpropyl), Aaa-3 is D-Val (R₄=isopropyl), Aaa-4 is Phe (R₅=benzyl), Aaa-5 is Z-Dhb (X₂=C═CHCH₃ with Z configuration), Aaa-6 is L-Val (R₆=isopropyl), Aaa-7 is D-allo-Ile (R₇₌₁-methylpropyl), and R₈ contains a hexapeptide derivative of the following formula (Formula VI):

Other preferred compounds are analogously related to the other kahalalides, and have amino acids and side chains in common with such compounds. Reference is made to the known structures of the kahalalides. For preference, a compound of this invention mimics a natural kahalalide, with modification, insertion or suppression at one or more points in the molecule.

Especially preferred are compounds which have the same amino acids as in a natural cyclic kahalalide compound, but differ in the side chain, especially in the acyl part. Such differences can include more or fewer methylene groups, typically at most a change of two methylene groups, and more or less substituents, notably the addition of halogen such as fluorine substituents.

As used herein, the term “organic group” means a hydrocarbon group that is classified as an aliphatic group, cyclic group, or combination of aliphatic and cyclic groups (e.g., aralkyl groups). In the context of the present invention, the term “aliphatic group” means a saturated or unsaturated linear or branched hydrocarbon. This term is used to encompass alkyl, alkenyl, and alkynyl groups, for example.

The term “alkyl group” means a saturated linear or branched hydrocarbon group including, for example, methyl, ethyl, isopropyl, isobutyl, t-butyl, heptyl, dodecyl, octadecyl, amyl, 2-ethylhexyl, 2-methylbutyl, 5-methylhexyl, 9-methyl-3-decyl, and the like, particularly alkyl groups which have a single branched methyl group. Suitably the alkyl group is long and has 1 to 20 carbon atoms, more typically 1 to 15 or 1 to 10 carbon atoms, or can be short and has 1 to 6 or 1 to 3 carbon atoms. The group R₁₁ is suited to the long carbon chains, and in general all the other alkyl groups are preferably short.

The term “alkenyl group” means an unsaturated, linear or branched hydrocarbon group with one or more carbon-carbon double bonds, such as a vinyl group. Suitably the alkenyl group has 2 to 8 or 2 to 4 carbon atoms.

The term “alkynyl group” means an unsaturated, linear or branched hydrocarbon group with one or more carbon-carbon triple bonds. Suitably the alkynyl group has 2 to 8 or 2 to 4 carbon atoms.

The term “cyclic group” means a closed ring hydrocarbon group that is classified as an alicyclic group, aromatic group, or heterocyclic group. The term “alicyclic group” means a cyclic hydrocarbon group having properties resembling those of aliphatic groups, and is suitably a mono- or bi-cycle with 4 to 10 carbon atoms. The term “aromatic group” or “aryl group” means a mono- or polycyclic aromatic hydrocarbon group, suitably a mono- or bi-cycle with 5 to 10 carbon atoms. The term “heterocyclic group” means a closed ring hydrocarbon in which one or more of the atoms in the ring is an element other than carbon (e.g., 1 to 3 of one or more of nitrogen, oxygen, sulfur, etc.), suitably a mono- or bi-cycle with 4 to 10 ring atoms.

As is well understood in this technical area, a large degree of substitution is not only tolerated, but is often advisable. Substitution is anticipated on the compounds of the present invention. As a means of simplifying the discussion and recitation of certain terminology used throughout this application, the terms “group” and “moiety” are used to differentiate between chemical species that allow for substitution or that may be substituted and those that do not allow or may not be so substituted. Thus, when the term “group” is used to describe a chemical substituent, the described chemical material includes the unsubstituted group and that group with O, N, or S atoms, for example, in the chain as well as carbonyl group or other conventional substitution. Where the term “moiety” is used to describe a chemical compound or substituent, only a unsubstituted chemical material is intended to be included. For example, the phrase “alkyl group” is intended to include not only pure open chain saturated hydrocarbon alkyl substituents, such as methyl, ethyl, propyl, isobutyl, and the like, but also alkyl substituents bearing further substituents known in the art, such as hydroxy, alkoxy, amino, carboxyl, carboxamido, halogen atoms, cyano, nitro, alkylsulfonyl, etc. Thus, “alkyl group” includes ether groups, haloalkyls, alcohols, thiols, carboxyl, amines, hydroxyalkyls, sulfoalkyls, etc. Haloalkyl groups are currently preferred. On the other hand, the phrase “alkyl moiety” is limited to the inclusion of only pure open chain saturated hydrocarbon alkyl substituents, such as methyl, ethyl, propyl, isobutyl, and the like.

In a particularly preferred embodiment of this invention, we provide a compound of the formula (A):

where each of Aa¹ to Aa⁶ with the adjacent respective —N— and —CO— represents an α or β amino acid, preferably an α amino acid, X is a linking group of Aa¹, preferably selected from amino, hydroxy or thiol, more preferably hydroxy, and R is a group optionally including one or more α or β amino acids, preferably α amino acids. In a variation, —CO-Aa⁶-N— may be absent, possibly along with —CO-Aa⁵-N— also being absent, or alternatively a group —CO-Aa⁷-N— may be interposed between Aa⁶ and Aa¹.

The amino acids can be of L or D configuration. Preferably the configuration is the same as the corresponding amino acid in a kahalalide compound especially kahalalide F. One or more of Aa¹ to Aa⁷ preferably corresponds to an amino acid at the same position in a natural kahalalide, or a congener thereof. In a particularly preferred embodiment, each amino acid is the same as in kahalalide F. Thus, for preference, Aa¹ is D-allo-Thr, Aa² is D-allo-Ile, Aa³ is D-Val, Aa⁴ is Phe, Aa⁵ is Z-Dhb, Aa⁶ is L-Val.

Where congeners are employed, suitable congeners have substitute amino acids where the substitution is made having regard to the structure of the respective amino acid in the natural kahalalide such as kahalalide F. Substitutes for threonine include serine and other homologues as well as cysteine and homologues. Substitutes for isoleucine include other amino acids with nonpolar groups, including alanine, valine, leucine, and proline, as well as analogues and homologues. In this respect, the showing of the nitrogen atoms —N— in the formula (A) does not exclude the possibility of ring formation such as occurs with proline. Substitutes for valine include isoleucine and the other amino acids with nonpolar groups, including analogues and homologues. Substitutes for phenylalanine include tryptophan and tyrosine. Substitutes for Dhb include other amino acids with such an alkenylidene substituent, including amino acids with C₃ or higher sidechains, as well as analogues and homologues.

Preferably Aa¹ is of the formula:

where Raa₁ is a sidechain carrying the linking X. Examples of sidechains include alkyl, aryl and aralkyl, especially alkyl, more typically alkyl of 1 to 4, such as 2 carbon atoms. Branched alkyl is preferred. The linking group X is suitably oxygen, with Aa₁ being preferably derived from threonine, but sulphur, amino (unsubstituted or substituted with alkyl, aryl or aralkyl), and other linkers can be employed. Suitably the group X is the only polar group in Aa¹. Aa¹ can be racemic, L or D, but is preferably in the D configuration.

Preferably Aa² is of the formula:

where Raa₂ is a sidechain such as alkyl, aryl and aralkyl, especially alkyl, more typically alkyl of 1 to 5, such as 3 carbon atoms. Branched alkyl is preferred, as in isoleucine. Suitably there are no polar substituents in Aa². Aa² can be racemic, L or D, but is preferably in the D configuration.

Preferably Aa³ is of the formula:

where Raa₃ is a sidechain such as alkyl, aryl and aralkyl, especially alkyl, more typically alkyl of 1 to 5 such as 3 carbon atoms. Branched alkyl is preferred, as in valine. Suitably there are no polar substituents in Aa³. Aa³ can be racemic, L or D, but is preferably in the D configuration.

Preferably Aa⁴ is of the formula:

where Raa₄ is a sidechain such as alkyl, aryl and aralkyl, especially aralkyl, more typically aralkyl of 7 to 10 such as 7 carbon atoms. Benzyl is preferred, as in phenylalanine. Suitably there are no polar substituents in Aa⁴. Aa⁴ can be racemic, L or D, but is preferably in the L configuration.

Preferably Aa⁵ is of the formula:

where Raa_(5a) and Raa_(5b) is each chosen from hydrogen, or a sidechain such as alkyl, aryl and aralkyl, especially alkyl, more typically alkyl of 1 to 4 such as 1 carbon atom. Preferably Raa_(5a) is hydrogen, giving a Z configuration as in the preferred a,b-didehydro-a-aminobutyric acid. Suitably there are no polar substituents in Aa⁵. Aa⁵ can be racemic, L or D, but is preferably in the L configuration.

Preferably Aa⁶ is of the formula:

where Raa₆ is a sidechain such as alkyl, aryl and aralkyl, especially alkyl, more typically alkyl of 1 to 5 such as 3 carbon atoms. Branched alkyl is preferred, as in valine. Suitably there are no polar substituents in Aa⁶. Aa⁶ can be racemic, L or D, but is preferably in the L configuration.

The amino acids Aa¹ to Aa⁷ can be as defined for the groups Aaa-1 to Aaa-7 of formula (II).

Preferably the side chain R comprises 5-MeHex-D-Val-L-Thr-L-Val-D-Val-D-Pro-L-Orn-D-allo-Ile, or a congener thereof, including analogues and homologues. Examples of congeners include those of the general formula (R^(t))_(m)-(amino acid)_(n)—, with m+n non-zero, where R^(t) represents a terminal group, suitably an alkyl, alkenyl, alkynyl, aryl, aralkyl, heteroaryl, heteroalkyl, alicyclic or other terminator, and -(amino acid)_(n)— represents an optional chain of amino acids.

A terminal alkyl group suitably has 1 to 12 carbon atoms, more typically 4 to 10 carbon atoms, and may be substituted and is preferably branched. Examples include butyl, pentyl, hexyl, heptyl, octyl, and other alkyl groups bearing 1 or more methyl or ethyl or longer side groups preferably of 1 to 6 carbon atoms, especially 5-methylhexyl and other alkyl groups with branching distal to the point of attachment to the rest of the molecule. Suitable substituents include halogen, hydroxy, alkoxy, amino, carboxyl, carboxamido, cyano, nitro, alkylsulfonyl, alkoxy, alkoxyalkyl, arylalkylaryl, heterocyclic, alicyclic, aryl, aralkyl and other groups mentioned herein. As appropriate, such substituents may bear further substituents, as for example a tolyl group. Halogen substituents are currently most preferred, especially 1 or more, such as 1 to 3, flourine atoms. Other terminal groups can be selected according to the guidance given in this text, and include alicyclic, aralkyl, aryl, heterocyclic or other groups, possibly with 1 or more, especially 1 to 3, substituents.

The side chain R—CO—N— can have hydrogen or a substituent on the nitrogen, such as alkyl, aryl or aralkyl group.

Suitable side chain congeners employ substitute amino acids chosen in accordance with the principles given before, with alternatives to isoleucine, valine and threonine being selected as for these amino acids in the cyclic part of the molecule, and alternatives to ornithine including lysine, histidine, arginine; alternatives to proline including alanine and other nonpolar amino acids such as glycine, isoleucine and the others previously mentioned. Typically the chain R has 0 to 10, more preferably 4 to 8, such as 5, 6 or 7, especially 7, amino acid residues. Where there are more than seven amino acids, then the extra amino acids are preferably naturally occurring amino acids, particularly those mentioned herein.

Racemic or L or D amino acids can be used. Preferably where amino acids are present in the side chain R, then one or more of them is in the configuration given for the naturally occurring sidechain. Reading from the cyclic hexapeptide, the amino acid residues are in the configuration DLDDLLD. The terminal alkyl group suitably has 1 to 12 carbon atoms, more typically 4 to 10 carbon atoms, and may be substituted and is preferably branched. Suitable substituents include halogen, hydroxy, alkoxy, amino, carboxyl, carboxamido, cyano, nitro, alkylsulfonyl and other groups mentioned herein. Halogen substituents are current most preferred.

More generally, the side chain R—CO—N— can be as defined for the side chain R₈—NH—CHR₇—CO—NH— in the compounds of formula (II), including compounds with mixtures of amino acids defined within formulae (III), (IV) and (V).

Although the preferred features have been described by reference to kahalalide F, other preferred compounds of this invention are provided by the application of the same principles to the design of mimics of other kahalalides. Thus, the amino acids and side chains can be changed, preferably while retaining the hydrophobic-hydrophilic balance between polar and nonpolar groupings.

Compounds of this invention have useful biological activity, including an antitumour activity.

Thus, the present invention provides a method of treating any mammal, notably a human, affected by cancer which comprises administering to the affected individual a therapeutically effective amount of a compound of the invention, or a pharmaceutical composition thereof.

The present invention also relates to pharmaceutical preparations, which contain as active ingredient a compound or compounds of the invention, as well as the processes for their preparation.

Examples of pharmaceutical compositions include any solid (tablets, pills, capsules, granules, etc.) or liquid (solutions, suspensions or emulsions) with suitable composition or oral, topical or parenteral administration, and they may contain the pure compound or in combination with any carrier or other pharmacologically active compounds. These compositions may need to be sterile when administered parenterally.

Administration of the compounds or compositions of the present invention may be by any suitable method, such as intravenous infusion, oral preparations, intraperitoneal and intravenous administration. We prefer that infusion times of up to 24 hours are used, more preferably 2-12 hours, with 2-6 hours most preferred. Short infusion times which allow treatment to be carried out without an overnight stay in hospital are especially desirable. However, infusion may be 12 to 24 hours or even longer if required. Infusion may be carried out at suitable intervals of say 2 to 4 weeks. Pharmaceutical compositions containing compounds of the invention may be delivered by liposome or nanosphere encapsulation, in sustained release formulations or by other standard delivery means.

The correct dosage of the compounds will vary according to the particular formulation, the mode of application, and the particular situs, host and tumour being treated. Other factors like age, body weight, sex, diet, time of administration, rate of excretion, condition of the host, drug combinations, reaction sensitivities and severity of the disease shall be taken into account. Administration can be carried out continuously or periodically within the maximum tolerated dose.

The compounds and compositions of this invention may be used with other drugs to provide a combination therapy. The other drugs may form part of the same composition, or be provided as a separate composition for administration at the same time or a different time. The identity of the other drug is not particularly limited, and suitable candidates include:

a) drugs with antimitotic effects, especially those which target cytoskeletal elements, including microtubule modulators such as taxane drugs (such as taxol, paclitaxel, taxotere, docetaxel), podophylotoxins or vinca alkaloids (vincristine, vinblastine);

b) antimetabolite drugs such as 5-fluorouracil, cytarabine, gemcitabine, purine analogues such as pentostatin, methotrexate);

c) alkylating agents such as nitrogen mustards (such as cyclophosphamide or ifosphamide);

d) drugs which target DNA such as the antracycline drugs adriamycin, doxorubicin, pharmorubicin or epirubicin;

e) drugs which target topoisomerases such as etoposide;

f) hormones and hormone agonists or antagonists such as estrogens, antiestrogens (tamoxifen and related compounds) and androgens, flutamide, leuprorelin, goserelin, cyprotrone or octreotide;

g) drugs which target signal transduction in tumour cells including antibody derivatives such as herceptin;

h) alkylating drugs such as platinum drugs (cis-platin, carbonplatin, oxaliplatin, paraplatin) or nitrosoureas;

i) drugs potentially affecting metastasis of tumours such as matrix metalloproteinase inhibitors;

j) gene therapy and antisense agents;

k) antibody therapeutics;

l) other bioactive compounds of marine origin, notably the ecteinascidins such as ecteinascidin 743 or the didemnins such as aplidine;

m) steroid analogues, in particular dexamethasone;

n) anti-inflammatory drugs, in particular dexamethasone; and

o) anti-emetic drugs, in particular dexamethasone.

The present invention also extends to the compounds of the invention for use in a method of treatment, and to the use of the compounds in the preparation of a composition for treatment of cancer.

Compounds of this invention are also expected to have antituberculosis activity.

According to this invention there is also provided a process for preparing compounds of this invention including kahalalide F, which comprises ring closing between Aa₃ and Aa₄. We have found that ring closing at this position gives a superior process. Ring closing can be preceded and/or followed by other modifications to the molecule, including forming or extending the side chain on Aa₁, and/or removing protecting groups and/or modifying substituents on the amino acids.

Thus, the process can be illustrated by the following scheme:

where R′ is a group R—CO—N— or a precursor therefor, and where one or more of the amino acids may have protecting groups, and where the —COOH of Aa³ and/or the —NH₂ of Aa⁴ may optionally be protected, activated or derivatised. Such procedures using precursors or of protection, activation or derivatisation are in themselves entirely conventional, and further details are not needed to practice the process.

The process of this invention can be carried out from starting materials in an enantio- and stereocontrolled and fast manner, taking advantages of the solid-phase synthetic methodology, where the molecule in construction is bounded to an insoluble support during all synthetic operations. Thus, excess of reagents and soluble by-products can be removed simply by washing the molecule-resin with suitable solvents. Large excesses of the soluble reagents can, therefore, be used in order to drive the reactions to completion in a short period of time, avoiding racemization (if applies) and other secondary reactions. The method is also amenable for automation.

The preferred embodiment of the synthetic process of the present invention is best represented in the Scheme 1, which is directed to the formation of compounds of the formula (II).

As shown above in Scheme 1, the preferred process for the synthetic formation of Kahalalide F (I) and derivatives and analogues is based in a solid-phase approach, see for example Lloyd-Williams, P., et al., Chemical Approaches to the Synthesis of Peptides and Proteins, CRC Press, Boca Raton (Fla.), 1997.

The process of Scheme 1 comprises the sequential steps of:

(a) incorporating an Fmoc-amino acid (Aaa3) onto a solid support (e.g., polystyrene, polyethylene grafted on polystyrene, and the like) containing a super-acid labile handle or linker (e.g., chlorotrityl, polyalkoxybenzyl, and the like) forming an ester bond;

(b) elongating the peptidic chain with three amino acids (Aaa₂, Aaa₁, Aaa₇) using a Fmoc/tBu strategy. For I, X₁=OH and introduced without protection. When X₁=NH₂, this is introduced with Alloc protection;

(c) incorporating (Aaa₆) using an Alloc/tbu strategy;

(d) elongating the peptidic chain with the remaining amino acids and R₁₁—COOH through Aaa₇ using a Fmoc/tBu strategy;

(e-1) elongating the peptidic chain with two amino acids [Aaa₅ (OH,H), Aaa₄] through Aaa₆ using an Alloc/tBu strategy. The OH attached to Aaa₅ is unprotected;

(e-2) dehydrating in solid-phase to give the peptide with Aaa₅; or

(e′-1) incorporating the dipeptide Alloc-Aaa₄-Aaa₅-OH, which has been combined and dehydrated in solution;

(f) removing the Alloc group of Aaa₄ while the peptide is still anchored to the solid support;

(g) cleaving the side-chain protected, if applies, peptide from the solid support;

(h) cyclizing the peptide in solution;

(i) removing TFA labile side chain protecting groups.

It will be appreciated that the particular choice of protecting groups is not critical, and other choices are widely available. For example, Bzl type groups can replace tBu/Boc; Boc instead of Fmoc; Fmoc instead of Alloc; Wang resin instead of chlorotrityl.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE PROCESS

The preferred process of the present invention is illustrated in Scheme 1. As shown therein, and as discussed in greater detail in the examples which follow below, this process was conducted as follows:

Fmoc-Aaa3-OH was incorporated preferably to a chlorotrityl-polystyrene resin, see Barlos, K.; Gatos, D.; Schafer, W. Angew. Chem. Int. Ed. Engl. 1991, 30, 590-593, in the presence of DIEA keeping the level of substitution of aprox. 0.15-0.5 mmol/g. The use of higher loadings brings the presence of terminated peptides in the final product, see Chiva, C.; Vilaseca, M.; Giralt, E.; Albericio, F. J. Pept. Sci. 1999, 5, 131-140.

Removal of the Fmoc group was carried out with piperidine-DMF (2:8, v/v) (1×1 min, 3×5 min, 1×10 min). Couplings of Fmoc-, Alloc-Aaa-OH, and R11-COOH (5 equiv) were carried out with HATU-DIEA, see Carpino, L. A.; El-Faham, A.; Minor, C. A.; Albericio, F. J. Chem. Soc., Chem. Commun. 1994, 201-203, (5:10) in DMF for 90 min. After the coupling ninhydrin test was carried out and if it was positive the coupling was repeated in the same conditions, otherwise the process was continued. Washings between deprotection, coupling, and, again, deprotection steps were carried out with DMF (5×0.5 min) and CH₂Cl₂ (5×0.5 min) using each time 10 mL solvent/g resin.

Incorporation of Alloc-Aaa6-OH (7 equiv) when X1=O was carried with equimolar amount of DIPCDI and 0.7 equiv of DMAP for 2 h. This coupling was repeated twice.

Removal of Alloc group was carried out with Pd(PPh₃)₄ (0.1 equiv) in the presence of PhSiH3 (10 equiv) under atmosphere of Ar, see Gómez-Martinez, P.; Thieriet, N.; Albericio, F.; Guibe, F. J. Chem. Soc. Perkin I 1999, 2871-2874.

Dehydration was carried out in solid-phase with EDC (water soluble carbodiimide, 100 equiv) in the presence of CuCl (60 equiv) in CH2Cl2-DMF (10:2) for 6 days. EDC/CuCl has been used by dehydration in solution of a residue of Thr in a fragment of Nisin. Fukase, K.; Kitazawa, M.; Sano, A.; Shimbo, K.; Horimoto, S.; Fujita, H.; Kubo, A.; Wakamiya, T.; Shibe, A. Bull. Chem. Soc. Jpn. 1992, 65, 2227-2240.

The dipeptide Alloc-Aaa₄-Aaa₅-OH (5 equiv), which was prepared in solution from Alloc-Aaa₄-OH and H-Aaa₅(OH, H)-OtBu with EDC, and posterior dehydration and treatment with TFA, was coupled with HATU-DIEA (5:10) for 16 h and recoupling for 3 h The use of other coupling reagents based in HOBt, such as HBTU or DIPCDI-HOBt, have led to incomplete incorporations of the dipeptide.

Cleavage of the protected peptide from the resin was accomplished by TFA-CH₂Cl₂ (1:99) (5×30 sec).

Cyclization step was carried out with DIPCDI-HOBt (3:3 equiv) in CH2Cl2-DMF for 2 hrs. Other methods, such as PyBOP/DIEA (3:6 equiv) in DMF can be also be used.

Final deprotection was carried out with TFA-H₂O (95:5) for 1 h.

EXAMPLES OF THE INVENTION Abbreviations

Abbreviations used for amino acids and the designations of peptides follow the rules of the IUPAC-IUB Commission of Biochemical Nomenclature in J. Biol. Chem. 1972, 247, 977-983. The following additional abbreviations are used: 4-AcBut-OH, 4-acetoxybutyric acid; AcButBut-OH, 4-(4-acetoxybutanoyloxy)-butyric acid; ACH, a-cyano-4-hydroxycinnamic acid; Alloc, allyloxycarbonyl; Boc, tert-butyloxycarbonyl; t-Bu, tert-Butyl; But-OH, butyric acid; Cl-TrtCl-resin, 2-chlorotrityl chloride-resin; Dap, 2,3-diaminopropionic acid; 4-DiMeABut-OH, N,N-dimethyl-4-aminobutyric acid; 3,3-DiMeBut-OH, 3,3-Dimethylbutyric acid; DHB, 2,5-dihydroxybenzoic acid; Z-Dhb, a,b-Didehydro-α-aminobutyric acid; DIEA, N,N-diisopropylethylamine; DMF, N,N-dimethylformanide; EDC, 1-ethyl-3-(3′-dimethylaminopropyl)carbodiimide hydrochloride; Etg, ethylglycine; ESMS, electrospray mass spectrometry; FABMS, fast atom bombardment mass spectrometry; Fmoc, 9-fluorenylmethoxycarbonyl; HATU, N-[(dimethylamino)-1H-1,2,3-triazolo-[4,5-b]pyridin-1-yl-methylene]-N-methylmethanaminium hexafluorophosphate N-oxide; HBTU, N-[(1H-benzotriazol-1-yl) (dimethylamino)methylene]-N-methylmethanaminium hexafluorophosphate N-oxide; 2-Hedo-OH, 2,4-hexadienoic acid; Hep-OH, heptanoic acid; HOAc, acetic acid, HOAt, 1-hydroxy-7-azabenzotriazole (3-hydroxy-3H-1,2,3-triazolo-[4,5-b]pyridine); HOBt, 1-hydroxybenzotriazole; IBut-OH, isobutyric acid; 3-MeBut-OH, 3-methylbutyric acid; 5-MeHex-OH, 5-methylhexanoic acid; MeOH, methanol; 4-MePen-OH, 4-methylpentanoic acid; NMM, N-methylmorpholine; 4-HOBut, 4-hydroxybutyric; (b-OH)Phe-OH, b-hydroxyphenylalanine; Lit-OH, Lithocholic acid; Pal, palmitic acid; D-Phe-OH, a,b-Didehydrophenylalanine; PyAOP, 7-azabenzotriazol-1-yl-N-oxy-tris(pyrrolidino)phosphonium hexafluorophosphate; PyBOP, benzotriazol-1-yl-N-oxy-tris(pyrrolidino)phosphonium hexafluorophosphate; SPS, solid-phase synthesis; TFA, trifluoroacetic acid; Tico-OH, tetraicosanoic acid. Amino acid symbols denote the L-configuration unless stated otherwise. All solvent ratios are volume/volume unless stated otherwise.

General Procedures. Cl-TrtCl-resin, Protected Fmoc-amino acid derivatives, HOBt, PyBOP, HATU were from PerSeptive Biosystems (Framingham, Mass.), Bachem (Bubendorf, Switzerland), NovaBiochem (Läufelfingen, Switzerland). Alloc-amino acids were preparated essentially as described by Dangles et al., see Dangles, O.; Guibé, F.; Balavoine, G.; Lavielle, S.; Marquet. A. J. Org. Chem. 1987, 52, 4984-4993, and 5-MeHex-OH through a malonic synthesis. DIEA, DIPCDI, EDC, Piperidine, TFA were from Aldrich (Milwaukee, Wis.). DMF and CH₂Cl₂ were from SDS (Peypin, France). Acetonitrile (HPLC grade) was from Scharlau (Barcelona, Spain). All commercial reagents and solvents were used as received with exception of DMF and CH₂Cl₂, which were bubbled with nitrogen to remove volatile contaminants (DMF) and stored over activated 4 Å molecular sieves (Merck, Darmstadt, Germany) (DMF) or CaCl₂ (CH₂Cl₂). Solution reactions were performed in round bottom flasks. Organic solvent extracts were dried over anhydrous MgSO₄, followed by solvent removal at reduced pressures and <40° C.

Solid-phase synthesis were carried out in polypropylene syringes (20, 10 mL) fitted with a polyethylene porous disc. Solvents and soluble reagents were removed by suction. Removal of the Fmoc group was carried out with piperidine-DMF (2:8, v/v) (1×1 min, 3×5 min, 1×10 min). Washings between deprotection, coupling, and, again, deprotection steps were carried out with DMF (5×0.5 min) and CH₂Cl₂ (5×0.5 min) using each time 10 mL solvent/g resin. Peptide synthesis transformations and washes were performed at 25° C. Syntheses carried out on solid-phase were controlled by HPLC of the intermediates obtained after cleaving with TFA-H₂O (9:1) for 60 min an aliquot (aprox. 10 mg) of the peptidyl-resin HPLC columns [Kromasil C₁₈ (Conditions A-F)/C₄ (Conditions G,H)] reversed-phase column, 4.6×250 mm, 10 mm) were from Akzo Nobel (Bohum, Sweden). Analytical HPLC was carried out on a Shimadzu instrument comprising two solvent delivery pumps (model LC-6A), automatic injector (model SIL-6B), variable wavelength detector (model SPD-6A), system controller (model SCL-6B) and plotter (model C-R6A). UV detection was at 220 nm, and linear gradients of CH₃CN (+0.036% TFA) into H₂O (+0.045% TFA) were run at 1.0 mL/min flow rate from: (Condition A) 1:9 to 10:0 over 30 min; (Condition B) 3:7 to 10:0 over 30 min; (Condition C) 1:19 to 19:1 over 30 min; (Condition D) 45:55 to 90:10 over 30 min; (Condition E) 45:55 to 6:4 over 30 min; (Condition F) isocratic 1:1; (Condition G) 3:7 to 1:0 over 30 min; (Condition H) 1:1 to 1:0 over 30 min.

MALDI-TOF- and ES-MS analysis of peptide samples were performed in a PerSeptive Biosystems Voyager DE RP, using CHCA or DHB matrices, and in a Micromass VG-quattro spectrometer. Peptide-resin samples were hydrolyzed in 12 N aqueous HCl-propionic acid (1:1), at 155° C. for 1-3 h and peptide-free samples were hydrolyzed in 6 N aqueous HCl at 155° C. for 1 h. Subsequent amino acid analyses were performed on a Beckman System 6300 autoanalyzer. ¹H-NMR (500 MHz, 200 MHz) and ¹³C-NMR (50 MHz) spectroscopy was performed on a Bruker DMX-500 (11.7 T) and Varian Gemini 200 (4.7 T). Chemical shifts (d) are expressed in parts per million downfield from TMS. Coupling constants are expressed in hertz.

Kahalalide F (I) Example 1 H-D-Val-O-TrtCl-resin

Cl-TrtCl-resin (1 g, 1.35 mmol/g) was placed in a 20 mL polypropylene syringe fitted with a polyethylene filter disk. The resin was then washed with CH₂Cl₂ (5×0.5 min), and a solution of Fmoc-D-Val-OH (92 mg, 0.27 mmol, 0.2 equiv) and DIEA (471 mL, 2.7 mmol, 2 equiv) in CH₂Cl₂ (2.5 mL) was added, and the mixture was stirred for 1 h. The reaction was terminated by addition of MeOH (800 mL), after a stirring of 15 min. The Fmoc-D-Val-O-TrtCl-resin was subjected to the following washings/treatments with CH₂Cl₂ (3×0.5 min), DMF (3×0.5 min), piperidine-CH₂Cl₂-DMF (1:9.5:9.5, 1×10 min), piperidine-DMF (1:4, 1×15 min), DMF (5×0.5 min), isopropanol (2×1 min), DMF (5×0.5 min), MeOH (2×1 min), and dried over vacuum. The loading as calculated by AAA was 0.15 mmol/g.

Example 2 Fmoc-D-allo-Ile-D-allo-Thr(Val-Alloc)-D-allo-Ile-D-Val-O-TrtCl-resin

Fmoc-D-allo-Ile-OH (265 mg, 0.75 mmol, 5 equiv), Fmoc-D-allo-Thr-OH (free hydroxy group) (256 mg, 0.75 mmol, 5 equiv), and Fmoc-D-allo-Ile-OH (265 mg, 0.75 mmol, 5 equiv) were added sequentially to the above obtained H-D-Val-O-TrtCl-resin using HATU (285 mg, 0.75 mmol, 5 equiv) and DIEA (261 mL, 1.5 mmol, 10 equiv) in DMF (2.5 mL). In all cases, after 90 min of coupling, the ninhydrin test was negative. Removal of Fmoc group and washings were carried out as described in General Procedures. Alloc-Val-OH (211 mg, 1.05 mmol, 7 equiv) was coupled with DIPCDI (163 mg, 1.05 mmol, 7 equiv) in the presence of DMAP (12.8 mg, 0.105 mmol, 0.7 equiv). This coupling was repeated in the same conditions twice. An aliqout of the peptidyl-resin was treated with TFA-H₂O (9:1) for 60 min and the HPLC (Condition A, t_(R) 25.9 min) of the crude obtained after evaporation showed a purity of >98%. ESMS, calcd for C₄₅H₆₃N₅O₁₁, 849.5. Found: m/z 850.1 [M+H]⁺.

Example 3 5-MeHex-D-Val-Thr(tBu)-Val-D-Val-D-Pro-Orn(Boc)-D-allo-Ile-D-allo-Thr(Val-Alloc)-D-allo-Ile-D-Val-O-TrtCl-resin

The Fmoc group was removed and Fmoc-Orn(Boc)-OH (341 mg, 0.75 mmol, 5 equiv), Fmoc-D-Pro-OH (253 mg, 0.75 mmol, 5 equiv), Fmoc-D-Val-OH (255 mg, 0.75 mmol, 5 equiv), Fmoc-Val-OH (255 mg, 0.75 mmol, 5 equiv), Fmoc-Thr(tBu)-OH (298 mg, 0.75 mmol, 5 equiv), Fmoc-D-Val-OH (255 mg, 0.75 mmol, 5 equiv), and 5-MeHex-OH (98 mg, 0.75 mmol, 5 equiv) were sequentially added to the above peptidyl-resin (Example 2) using HATU (285 mg, 0.75 mmol, 5 equiv) and DIEA (261 mL, 1.5 mmol, 10 equiv) in DMF (2.5 mL). In all cases, after 90 min of coupling, the ninhydrin or chloranil (after incorporation of D-Val) tests were negative. Removal of Fmoc group and washings were carried out as described in General Procedures. An aliqout of the peptidyl-resin was treated with TFA-H₂O (9:1) for 60 min and the HPLC (Condition B, t_(R) 17.2 min) of the crude obtained after evaporation showed a purity of >82%. ESMS, calcd for C₆₆H₁₁₆N₁₂O₁₇, 1,348.9. Found: m/z 1,350.0 [M+H]⁺.

Example 4 5-MeHex-D-Val-Thr(tBu)-Val-D-Val-D-Pro-Orn(Boc)-D-allo-Ile-D-allo-Thr(Val-Thr-Phe-Alloc)-D-allo-Ile-D-Val-O-TrtCl-resin

Alloc group was removed with Pd(PPh₃)₄ (17.3 mg, 0.015 mmol, 0.1 equiv) in the presence of PhSiH₃ (185 μL, 1.5 mmol, 10 equiv) under atmosphere of Ar. Fmoc-Thr-OH (free hydroxy group) (256 mg, 0.75 mmol, 5 equiv) and Alloc-Phe-OH (187 mg, 0.75 mmol, 5 equiv) were added sequentially to the above peptidyl-resin (Example 3) using HATU (285 mg, 0.75 mmol, 5 equiv) and DIEA (261 mL, 1.5 mmol, 10 equiv) in DMF (2.5 mL). In all cases, after 90 min of coupling, the ninhydrin test was negative. Removal of Fmoc group and washings were carried out as described in General Procedures. An aliqout of the peptidyl-resin was treated with TFA-H₂O (9:1) for 60 min and the HPLC of the crude obtained after evaporation showed a purity by HPLC (Condition B, t_(R) 17.8 min) of >70%. ESMS, calcd for C₇₉H₁₃₂N₁₄O₂₀, 1,597.0. Found: m/z 1,598.2 [M+H]⁺.

Example 5 5-MeHex-D-Val-Thr(tBu)-Val-D-Val-D-Pro-Orn(Boc)-D-allo-Ile-D-allo-Thr(Val-Z-Dhb-Phe-H)-D-allo-Ile-D-Val-O-TrtCl-resin (via dehydration in solid-phase)

The above peptidyl-resin (Example 4) was treated with EDC (2.88 g, 15 mmol, 100 equiv), CuCl (891 mg, 9 mmol, 60 equiv) in CH₂Cl₂-DMF (10:2) (12 mL) for 6 days. After extensively washings with DMF, CH₂Cl₂, and DMF, the Alloc group was removed with Pd(PPh₃)₄ (17.3 mg, 0.015 mmol, 0.1 equiv) in the presence of PhSiH₃ (185 μL, 1.5 mmol, 10 equiv) under atmosphere of Ar. The final loading as calculated by AAA was 0.11 mmol/g (92% overall yield). An aliquot of the peptidyl-resin was treated with TFA-H₂O (9:1) for 60 min and the HPLC (Condition B, t_(R) 17.2 min) of the crude obtained after evaporation showed a purity by of >70%. ESMS, calcd for C₇₅H₁₂₆N₁₄O₁₇, 1495.0 Found: m/z 1,496.0 [M+H]⁺.

Example 6 5-MeHex-D-Val-Thr(tBu)-Val-D-Val-D-Pro-Orn(Boc)-D-allo-Ile-D-allo-Thr(Val-Z-Dhb-Phe-H)-D-allo-Ile-D-Val-OH

The protected peptide was cleaved from the resin (0.5 g, 55.9 μmol) by TFA-CH₂Cl₂ (1:99) (5×30 see). The combined filtrates were evaporated to dryness under reduced pressure and lyophilized, to give 80.2 mg (48.5 μmol, 87% yield) of the title compound with a purity of >70% as checked by HPLC (Condition B, t_(R) 25.7 min). ESMS, calcd for C₈₄H₁₄₂N₁₄O₁₉, 1,651.1. Found: m/z 1,652.3 [M+H]⁺.

Example 7 Kahalalide F (I)

The protected peptide (Example 6) (40.0 mg, 24 μmol) was dissolved in DMF (25 mL), and PyBOP (37.8 mg, 73 μmol, 3 equiv) and DIEA (25 mL, 145 μmol, 6 equiv) were added. The mixture was allowed to stir for 1 h, and then the solvent was removed by evaporation under reduced pressure. The protected cyclic peptide was dissolved in TFA-H₂O (19:1, 5 mL) and the mixture was allowed to stir for 1 h. The solvent was removed by evaporation under reduced pressure, and then H₂O (5 mL) was added and lyophilized. The crude product was purified by medium pressure chromatography (Vydac C₁₈ 15-20 μm, 300 Å, 240×24 mm), linear gradient from 20% to 60% of acetonitrile (+0.05% TFA) in water (+0.05% TFA) in 5 h (300 mL each solvent), 120 mL/h, detection at 220 nm, to give the title product (5.0 mg, 3.4 μmol, 14% yield). MALDI-TOF-MS, calcd for C₇₅H₁₂₄N₁₄O₁₆, 1,477.9. Found: m/z 1,478.7 [M+H]⁺, 1,500.6 [M+Na]⁺, 1,516.5 [M+K]⁺. The product co-eluted by HPLC [Condition D (t_(R) 12.5 min), E (t_(R) 17.4 min), and F(t_(R) 12.1 min)] with an authentic sample of Kahalalide F. The ¹H-NMR (500 MHz, d⁶-DMSO) spectrum of the compound was identical to the natural product (data shown in Table I).

TABLE I RESIDUE N—H Hα Hβ OTHER (Z)-Dhb 9.69 (s) — 6.34 1.26 (d, J = 7.5 Hz, (q, J = γ-CH₃) 7.0 Hz) D-al.lo-Ile 1 8.82 (d, 4.31 1.73 1.31, 1.02, 0.77 (γ- J = 10.0 Hz) CH₂, γ-CH₃, δ- CH₃) L-Phe 8.79 (d, J = 5.5 Hz) 4.42 2.93 7.20 (1H Ar, m) (m) 7.28 (4H Ar, m) D-al.lo-Thr 8.56 (d, J = 8.0 Hz) 4.53 4.96 1.07 (δ, J = 6.5 Hz, (m) γ-CH₃) D-Val 3 8.10 (d, J = 8.5 Hz) 4.26 1.94 0.86 (2 γ-CH₃) L-Orn 7.95 (d, J = 8.5 Hz) 4.49 1.48 1.67 (γ-CH₂), (2H) 2.74 (bs, δ-CH₂), 7.69 (ε-NH₃ ⁺) D-al.lo-Ile 2 7.90 (d) 4.37 1.69 1.30, 1.03, 0.77 (γ- CH₂, γ-CH₃, δ- CH₃) D-Val 5 7.88 (d) 4.23 1.96 0.84 (2 γ-CH₃) L-Thr 7.82 (d, J = 8.0 Hz) 4.26 3.97 4.88 (d, J = 5.0 Hz, (m) OH), 0.98 (d, J = 6.5 Hz, γ-CH₃) D-Val 2 7.62 (d, J = 8.5 Hz) 4.46 2.17 0.77 (γ-CH₃), 0.62 (d, J = 7.0 Hz, γ-CH₃) L-Val 4 7.57 (d, J = 8.5 Hz) 4.28 1.98 0.80 (2 γ-CH₃) L-Val 1 6.76 (d, J = 9.0 Hz) 3.86 1.39 0.62 (d, J = 7.0 Hz, γ-CH₃), 0.58 (d, J = 6.0 Hz, γ-CH₃) D-Pro — 4.36 2.03, 1.87, 1.79 (β-CH₂, γ-CH₂), 3.76 (1H, m, δ-CH₂), 3.53 (1H, m, —CH₂) 5-MeHex — 2.13 1.47 (β-CH₂, δ-CH), (2H) 1.11 (γ-CH₂), 0.82 (2 ε-CH₃)

Example 7bis 5-MeHex-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-Val-Phe-Z-Dhb-Val)

Obtained as a side product during the preparation (racemization during the cyclization step) of Example 7. The product was characterized by HPLC (t_(R) 17.4 min, Condition B) and ESMS, calcd for C₇₅H₁₂₄N₁₄O₁₆, 1,477.9. Found: m/z 1,501.3 [M+Na]⁺, 1,517.3 [M+K]⁺.

Kahalalide F (I) Example 8 Alloc-Phe-Thr-OtBu

H-Thr-OtBu.HCl (3.1 g, 15 mmol, 1.3 equiv) was dissolved in CH₂Cl₂ (30 mL) and DIEA (2.9 mL, 17 mmol, 1.5 equiv) was added and the mixture allowed to stir for 30 min. Alloc-Phe-OH (2.8 g, 11 mmol, 1 equiv) and EDC (2.8 g, 15 mmol, 1.3 equiv) in CH₂Cl₂ (35 mL) was then added and the reaction was stirred for 18 h. The organic reaction mixture was washed with H₂O (3×25 mL), dried (MgSO₄) and concentrated in vacuo. The resultant oil (4.12 g) was purified by flash chromatography [CHCl₃-MeOH—HOAc (9:1:0.2)] to give the title product (3.25 g, 8 mmol, 71% yield), which was characterized by analytical HPLC (t_(R) 20.9 min, >98% purity; Condition C); ESMS, calcd for C₂₁H₃₀N₂O₆, 406.2. Found: m/z 408.0 [M+H]⁺; ¹H-NMR (200 MHz, CDCl₃): 7.1-7.3 (5H, m, Ar); 6.89 (1H, d, J=8.8 Hz, NH); 5.7-5.9 (1H, m, CH allyl); 5.56 (1H, d, J=8.0 Hz, OH); 5.2-5.3 (2H, m, CH₂ g-allyl); 4.52 (2H, d, J=5.4 Hz, CH₂ a-allyl); 4.45 (1H, dd, J=8.4 Hz, 2.8 Hz, a-CH Thr); 4.22 (1H, dq, J=6.2 Hz, J=3.0 Hz, b-CH Thr); 3.0-3.2 (2H, m, b-CH₂ Phe); 1.47 (9H, s, tBu); 1.15 (3H, d, J=6.6 Hz, g-CH₃ Thr); ¹³C-NMR (50 MHz, CDCl₃): 172.2 (CO), 169.5 (CO); 156.0 (CO); 136.1 (Cq, Ar); 132.5 (CH, allyl); 129.3 (CH, Ar); 128.5 (CH, Ar); 126.9 (CH, Ar); 117.7 (CH₂, allyl); 82.7 (Cq, teu); 68.5 (b-CH Thr); 65.9 (CH₂, allyl); 58.0 (a-CH Thr); 56.2 (a-CH Phe); 38.3 (b-CH₂ Phe); 28.0 (CH₃, tBu); 20.8 (g-CH₃ Thr).

Example 9 Alloc-Phe-Z-Dhb-OtBu

Alloc-Phe-Thr-OtBu (3.25 g, 8.0 mmol), EDC (9.90 g, 52 mmol, 6.5 equiv), and CuCl (2.14 g, 22 mmol, 2.7 equiv) were dissolved in CH₂Cl₂— anhydrous DMF (65 ml, 12:1) under N₂ and the mixture was allowed to stir for 2 days under N₂. The organic solvent was removed in vacuo and the residue was taken in a saturated solution of EDTA (100 mL), which was extracted with EtOAc (3×50 mL). The combined organic solution was washed with brine (3×60 mL) dried (MgSO₄) and concentrated in vacuo to give a pale yellow solid (2.8 g), was purified by flash chromatography [CHCl₃-MeOH—HOAc (9:1:0.1)] to give the title product (2.6 g, 6.7 mmol, 84% yield), which was characterized by analytical HPLC (t_(R) 23.1 min, >95% purity; Condition C); ESMS, calcd for C₂₁H₂₈N₂O₅, 388.2. Found: m/z 389.6 [M+H]⁺; ¹H-NMR (200 MHz, CDCl₃): 7.2-7.4 (5H, m, Ar); 6.69 (1H, q, J=7.4 Hz, CH Dhb); 5.8-6.0 (1H, m, CH allyl); 5.2-5.3 (2H, m, CH₂ g-allyl); 4.5-4.6 (2H, m, a-CH₂ allyl); 3.1-3.3 (2H, m, b-CH₂ Phe); 1.67 (3H, d, J=7.2 Hz, CH₃ Dhb); 1.47 (9H, s, tBu); ¹³C-NMR (50 MHz, CDCl₃): 168.9 (CO); 163.1 (CO); 156.0 (CO); 136.0 (Cq, Ar); 132.6, 132.3 (CH, allyl; b-CH Dhb); 129.3 (CH, Ar); 128.7 (CH, Ar); 127.0 (CH, Ar); 117.9 (CH₂, allyl); 81.7 (Cq, tBu); 66.0 (CH₂, allyl); 56.3 (a-CH Phe); 38.2 (b-CH₂ Phe); 28.0 (CH₃, tBu); 14.7 (CH₃ Dhb).

Example 10 Alloc-Phe-Z-Dhb-OH

Alloc-Phe-Z-Dhb-OtBu (2.6 g, 6.7 mmol) was dissolved in TFA-CH₂Cl₂—H₂O (90:8:2, 5.5 mL) and the mixture was allowed to stir for 3 h. The organic reaction was concentrated in vacuo to give the title product (2.2 g, 6.6 mmol, 99% yield), which was characterized by analytical HPLC (t_(R) 17.0 min, >95% purity; Condition C); ESMS, calcd for C₁₇H₂O N₂O₅, 332.1. Found: m/z 333.7 [M+H]⁺; ¹H-NMR (200 MHz, CD₃OD): 7.2-7.3 (5H, m, Ar); 6.84 (1H, q, J=7.2 Hz, CH Dhb); 5.8-6.0 (1H, m, CH allyl); 5.1-5.3 (2H, m, CH₂ g-allyl); 4.4-4.5 (2H, m, a-CH₂ allyl); 3.2-3.3 (1H, m, b-CH₂ Phe); 2.8-3.0 (1H, m, b-CH₂ Phe); 1.66 (3H, d, J=7.4 Hz, CH₃ Dhb); ¹³C-NMR (50 MHz, CD₃OD): 173.1 (CO); 138.5 (Cq, Ar); 136.7, 134.1 (CH, allyl; b-CH Dhb); 130.3 (CH, Ar); 129.4 (CH, Ar); 127.7 (CH, Ar); 117.4 (CH₂, allyl); 66.6 (CH₂, allyl); 57.8 (a-CH Phe); 39.1 (b-CH₂ Phe); 14.1 (CH₃ Dhb).

Example 11 5-MeHex-D-Val-Thr(tBu)-Val-D-Val-D-Pro-Orn(Boc)-D-allo-Ile-D-allo-Thr(Val-Alloc)-D-allo-Ile-D-Val-O-TrtCl-resin

Cl-TrtCl-resin (0.45 g, 1.35 mmol/g) was placed in a 10 mL polypropylene syringe fitted with a polyethylene filter disk. The peptidyl-resin was obtained following the same procedure described in Examples 1-3 except that in the coupling of the first amino acid (Fmoc-D-Val-OH) to the resin 0.3 equiv instead of 0.2 equiv were used. The initial loading as calculated by AAA was 0.29 mmol/g. Once the aminoacids were coupled, an aliquot of the peptidyl-resin was treated with TFA-H₂O (9:1) for 60 min and the HPLC (Condition B, t_(R) 17.3 min) of the crude obtained after evaporation showed a purity of >80%. ESMS, calcd for C₆₆H₁₁₆N₁₂O₁₇, 1,348.9. Found: m/z 1,350.1 [M+H]⁺.

Example 12 5-MeHex-D-Val-Thr(tBu)-Val-D-Val-D-Pro-Orn(Boc)-D-allo-Ile-D-allo-Thr(Val-Z-Dhb-Phe-Alloc)-D-allo-Ile-D-Val-O-TrtCl-resin Via Incorporation of the Dipeptide

The peptidyl-resin was treated with Pd(PPh₃)₄ (15.1 mg, 0.013 mmol, 0.1 equiv) in the presence of PhSiH₃ (161 μL, 1.3 mmol, 10 equiv) under atmosphere of Ar, for removing the Alloc group. Alloc-Phe-Z-Dhb-OH (217 mg, 0.65 mmol, 5 equiv) and HATU (249 mg, 0.65 mmol, 5 equiv) were dissolved in DMF (1.25 mL) and added to peptidyl-resin, then DIEA (228 μL, 1.3 mmol, 10 equiv) was added and the mixture stirred overnight. After washings, the coupling was repeated with the same amount of reagents for 3 h., when the ninhydrin test was negative. After washings with DMF and CH₂Cl₂, an aliquot of the peptidyl-resin was treated with TFA-H₂O (9:1) for 60 min and the HPLC (Condition B, t_(R) 18.3 min) of the crude obtained after evaporation showed a purity by of >80%. MALDI-TOF-MS, calcd for C₇₉H₁₃₀N₁₄O₁₉, 1,579.0. Found: m/z 1,580.3 [M+H]⁺, 1,602.2 [M+Na]⁺, 1,618.2 [M+K]⁺.

Example 13 5-MeHex-D-Val-Thr(tBu)-Val-D-Val-D-Pro-Orn(Boc)-D-allo-Ile-D-allo-Thr(Val-Z-Dhb-Phe-H)-D-allo-Ile-D-Val-OH

The Alloc group from peptidyl-resin (Example 12) was removed with Pd(PPh₃)₄ (15.1 mg, 0.013 mmol, 0.1 equiv) in the presence of PhSiH₃ (161 μL, 1.3 mmol, 10 equiv) under atmosphere of Ar. The final loading as calculated by AAA was 0.16 mmol/g (79% overall yield). The protected peptide was cleaved from the resin (235 mg, 37.5 mmol) by TFA-CH₂Cl₂ (1:99) (5×30 sec). The combined filtrates were evaporated to dryness under reduced pressure and lyophilized, to give 40.5 mg (24.5 mmol, 65%) of the title compound with a purity >80% as checked by HPLC (Condition B, t_(R) 24.3 min). MALDI-TOF-MS, calcd for C₈₄H₁₄₂N₁₄O₁₉, 1,651.1. Found: m/z 1,674.8 [M+Na]⁺, 1,690.8 [M+K]⁺.

Example 14 Kahalalide F (I)

The protected peptide (Example 13) (38.5 mg, 23 μmol) was dissolved in DMF (25 mL), and PyBOP (36.4 mg, 70 μmol, 3 equiv) and DIEA (24 mL, 140 μmol, 6 equiv) were added. The mixture was allowed to stir for 1 h, and then the solvent was removed by evaporation under reduced pressure. The protected cyclic peptide was dissolved in TFA-H₂O (19:1, 5 mL) and the mixture was allowed to stir for 1 h. The solvent was removed by evaporation under reduced pressure, and then H₂O (5 mL) was added and lyophilized. The crude product was purified as described in Example 7 to give the title product (3.6 mg, 2.4 μmol, 10% yield), which was identical to the one obtained in Example 7.

5-MeHex-D-Val-Thr-D-Val-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val) (structure assigned to Kahalalide F by Goetz, G., et al. Tetrahedron, 1999, vol. 55, pp. 7739-7746)

Example 15 5-MeHex-D-Val-Thr-D-Val-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val) (via dehydration in solid-phase)

Experimental procedures as described in Examples 1-7 were carried out with the only exception that, in Example 3, Fmoc-Val-OH was incorporated to D-Pro-peptidyl-resin and then after removal of the Fmoc group, the Fmoc-D-Val-OH was incorporated. The final loading as calculated by AAA was 0.106 mmol/g (87% overall yield), the cleavage yield was of the 83%, and 4.7 mg of the title compound were obtained, which represented a 13% overall yield in cyclization, deprotection and purification steps. This product eluted in HPLC 0.8-1.9 min later than an authentic sample of Kahalalide F [Condition D (t_(R) 13.3 vs 12.5 min), E (t_(R) 18.8 vs 17.4 min), and F(t_(R) 14.0 vs min)]. MALDI-TOF-MS, calcd for C₇₅H₁₂₄N₁₄O₁₆, 1,477.9. Found: m/z 1,478.7 [M+H]⁺, 1,500.7 [M+Na]⁺, 1,516.6 [M+K]⁺.

The ¹H-NMR (500 MHz, d⁶-DMSO) spectrum of the compound (Tables II and III) was different from the one obtained for an authentic sample of Kahalalide F. The greatest difference was that the synthetic compound obtained, showed two conformations dued to a cis-trans equilibrium between L-Val-D-Pro residues which was not observed neither in the natural product nor in the isomer obtained in example 7.

TABLE II (Major, trans isomer) RESIDUE N—H Hα Hβ OTHER (Z)-Dhb 9.67 (s) — 6.33 (q) 1.27 (d, J = 7.0 Hz, γ-CH₃) D-al.lo-Ile 1 8.80 (d) 4.31 1.73 1.32, 0.77 (γ-CH₂, γ-CH₃, δ-CH₃) L-Phe 8.78 (d, J = 5.5 Hz) 4.43 2.93 7.20 (1H Ar, m) (m) 7.28 (4H Ar, m) D-al.lo-Thr 8.58 (d, J = 9.0 Hz) 4.53 4.95 1.07 (d, J = 6.5 Hz, (m) γ-CH₃) L-Val 3 7.97 (d, J = 8.0 Hz) 4.34 1.94 0.84 (2 γ-CH₃) L-Orn 7.77 (d, J = 8.5 Hz) 4.47 1.46 1.66 (γ-CH₂), (2H) 2.72 (bs, δ-CH₂), 7.66 (ε-NH₃ ⁺) D-al.lo-Ile 2 7.87 (d, J = 8.5 Hz) 4.37 1.68 0.75 (δ-CH₃ o d- CH₃ and γ-CH₃) D-Val 5 7.90 4.22 1.95 0.85 (2 γ-CH₃) L-Thr 7.90 (d) 4.24 4.02 4.98 (OH), 1.02 (γ- CH₃) D-Val 2 7.63 (d, J = 8.5 Hz) 4.45 2.18 0.77 (γ-CH₃), 0.62 (γ-CH₃) D-Val 4 7.56 (d, J = 9.0 Hz) 4.34 2.02 0.84 (γ-CH₃), 0.79 (γ-CH₃), L-Val 1 6.75 (d) 3.86 1.39 0.62 (2 γ-CH₃) D-Pro — 4.30 2.03, 1.81, 1.73 (β-CH₂, γ-CH₂), 3.73 (1H, m, δ-CH₂), 3.52 (1H, m, δ-CH₂) 5-MeHex — 2.08 1.48 (b-CH₂, δ-CH), (1H) 1.11 (γ-CH₂), 2.15 0.82 (2 ε-CH₃) (1H)

TABLE III (Minor, cis isomer) RESIDUE N—H Hα Hβ OTHER (Z)-Dhb 9.63 (s) — 6.33 (q) 1.28 (d, J = 6.5 Hz, γ-CH₃) D-al.lo-Ile 1 8.76 (d) 4.30 1.71 1.33, 0.76 (γ-CH₂, γ-CH₃, δ-CH₃) L-Phe 8.78 (d, J = 5.5 Hz) 4.43 2.93 7.20 (1H Ar, m) (m) 7.28 (4H Ar, m) D-al.lo-Thr 8.58 (d, J = 9.0 Hz) 4.53 4.95 1.00 (γ-CH₃) (m) L-Val 3 8.06 (d, J = 8.5 Hz) 4.11 1.81 0.71 (γ-CH₃), 0.60 (γ-CH₃) L-Orn 8.37 (d, J = 9.0 Hz) 4.62 1.52 1.64 (γ-CH₂), (2H) 2.78 (bs, δ-CH₂), 7.66 (ε-NH₃ ⁺) D-al.lo-Ile 2 8.09 (d, J = 9.0 Hz) 4.42 1.64 0.77 (δ-CH₃ or d- CH₃ and γ-CH₃) D-Val 5 7.90 4.22 1.95 0.85 (2 γ-CH₃) L-Thr 7.88 (d) 4.23 3.99 4.93 (OH), 1.02 (γ- CH₃) D-Val 2 7.63 (d, J = 8.5 Hz) 4.45 2.18 0.77 (γ-CH₃), 0.62 (γ-CH₃) D-Val 4 7.49 (d, J = 9.0 Hz) 4.34 1.94 0.79 (γ-CH₃), 0.73 (γ-CH₃), L-Val 1 6.72 (d) 3.84 1.38 0.62 (2 γ-CH₃) D-Pro — 4.93 2.06, 1.89, 1.75 (β-CH₂, γ-CH₂), 3.3 (m, δ-CH₂) 5-MeHex — 2.08 1.48 (β-CH₂, δ-CH), (1H) 1.11 (γ-CH₂), 0.82 (2 ε-CH₃) 2.15 (1H)

Example 15bis 5-MeHex-D-Val-Thr-D-Val-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-Val-Phe-Z-Dhb-Val)

Obtained as a side product during the preparation (racemization during the cyclization step) of Example 15. The product was characterized by HPLC (t_(R) 17.6 min, Condition B) and MALDI-TOF-MS, calcd for C₇₅H₁₂₄N₁₄O₁₆, 1,477.9. Found: m/z 1,479.3 [M+H]⁺, 1,501.2 [M+Na]⁺, 1,517.2 [M+K]⁺.

Example 16 5-MeHex-D-Val-Thr-D-Val-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val) Via Incorporation of the Dipeptide

Experimental procedures as described in Examples 8-14 were carried out with the only exception that, as in Example 14, Fmoc-Val-OH was incorporated to D-Pro-peptidyl-resin and then after removal of the Fmoc group, the Fmoc-D-Val-OH was incorporated. The final loading as calculated by AAA was 0.16 mmol/g (79% overall yield), the cleavage yield was of the 78%, and 3.4 mg of the title compound were obtained, which represented a 10% overall yield in cyclization, deprotection and purification steps. The product purified was identical to the one obtained in Example 15.

Hamann et al. Kahalalide B [5-MeHex-Tyr-cyclo(D-Ser-Phe-D-Leu-Pro-Thr-Gly)]

Example 17 H-Thr(tBu)-O-TrtCl-resin

Cl-TrtCl-resin (0.5 g, 1.35 mmol/g) was placed in a 10 mL polypropylene syringe fitted with a polyethylene filter disk. The resin was then washed with CH₂Cl₂ (5×0.5 min), and a solution of Fmoc-Thr(tBu)-OH (54 mg, 0.135 mmol, 0.2 equiv) and DIEA (235 mL, 1.35 mmol, 2 equiv) in CH₂Cl₂ (1.25 mL) was added, and the mixture was stirred for 1 h. The reaction was terminated by addition of MeOH (400 mL), after a stirring of 15 min. The Fmoc-Thr(tBu)-O-TrtCl-resin was subjected to the following washings/treatments with CH₂Cl₂ (3×0.5 min), DMF (3×0.5 min), piperidine-CH₂Cl₂-DMF (1:9.5:9.5, 1×10 min), piperidine-DMF (1:4, 1×15 min), DMF (5×0.5 min), isopropanol (2×1 min), DMF (5×0.5 min), MeOH (2×1 min), and dried over vacuum. The loading as calculated by AAA was 0.15 mmol/g.

Example 18 5-MeHex-Tyr-D-Ser(Gly-H)-Phe-D-Leu-Pro-Thr-OH

Fmoc-Pro-OH (178 mg, 0.53 mmol, 7 equiv), Fmoc-D-Leu-OH (187 mg, 0.53 mmol, 7 equiv), Fmoc-Phe-OH (204 mg, 0.53 mmol, 7 equiv), Fmoc-D-Ser-OH (free hydroxy group) (173 mg, 0.53 mmol, 7 equiv), Fmoc-Tyr(tBu)-OH (243 mg, 0.53 mmol, 7 equiv), and 5-MeHex-OH (69 mg, 0.53 mmol, 7 equiv) were added sequentially to the above obtained H-Thr(tBu)-O-TrtCl-resin using DIPCDI (82 μL, 0.53 mmol, 7 equiv) and HOBt (81 mg, 0.53 mmol, 7 equiv) in DMF (1.25 mL). In all cases except for D-Ser, after 90 min of coupling, the ninhydrin test was negative. Fmoc-D-Ser-OH (173 mg, 0.53 mmol, 7 equiv) was recoupled with HATU (201 mg, 0.53 mmol, 7 equiv) in the presence of DIEA (184 μL, 1.06 mmol, 14 equiv) in DMF for 90 min. Removal of Fmoc group and washings were carried out as described in General Procedures. Boc-Gly-OH (119 mg, 0.68 mmol, 9 equiv) was coupled with DIPCDI (105 μL, 0.68 mmol, 9 equiv) in the presence of DMAP (8.3 mg, 68 μmol, 0.9 equiv) for 2.5 h. The coupling was repeated with fresh reagents for 1.5 h. The final loading was 0.10 mmol/g, which represented a 77% synthesis yield. The unprotected peptide was cleaved from the resin (525 mg, 54 μmol) by TFA-H₂O (92:8) for 2 h. The combined filtrates were evaporated to dryness under reduced pressure, H₂O (5 mL) was added, and the solution lyophilized to give 43.0 mg (48.0 μmol, 89% yield) of the title compound with a purity of >85% as checked by HPLC (Condition A, t_(R) 18.5 min). ESMS, calcd for C₄₅H₆₅N₇O₁₂, 895.5. Found: m/z 896.6 [M+H]⁺.

Example 19 Kahalalide B [5-MeHex-Tyr-cyclo(D-Ser-Phe-D-Leu-Pro-Thr-Gly)]

The unprotected peptide (Example 18) (40.5 mg, 45 μmol) was dissolved in DMF (48 mL), and PyBOP (70 mg, 0.135 mmol, 3 equiv) and DIEA (47 mL, 0.271 mmol, 6 equiv) were added. The mixture was allowed to stir for 2 h, and then the solvent was removed by evaporation under reduced pressure, H₂O (5 mL) was added, and the solution lyophilized. The crude product was purified by medium pressure chromatography (Vydac C₁₈ 15-20 μm, 300 Å, 240×24 mm), linear gradient from 20% to 60% of acetonitrile (+0.05% TFA) in water (+0.05% TFA) in 5 h (300 mL each solvent), 120 mL/h, detection at 220 nm, to give the title product (8.7 mg, 9.9 μmol, 22% yield). The product was characterized by HPLC (Condition A, t_(R) 21.6 min) and MALDI-TOF-MS, calcd for C₄₅H₆₃N₇O₁₁, 877.5. Found: m/z 878.7 [M+H]⁺, 900.6 [M+Na]⁺, 916.5 [M+K]⁺. AAA: Gly 1.02 (1), Thr 0.95 (1), Phe 0.99 (1), Ser 1.00 (1), Pro 1.20 (1), Leu 1.00 (1), Tyr 0.87 (1).

Example 20 5-MeHex-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Etg-Val)

Experimental procedures as described in Examples 1-4 and 6-7, starting with 200 mg of resin, were carried out with the only exception that, in Example 4, Fmoc-Thr-OH was replaced by Fmoc-Etg-OH. The product was characterized by HPLC (t_(R) 16.8 min, Condition B) and MALDI-TOF-MS, calcd for C₇₅H₁₂₆ N₁₄O₁₆, 1,479.0. Found: m/z 1,480.2 [M+H]⁺, 1,502.2 [M+Na]⁺, 1,518.0 [M+K]⁺.

Example 20b 5-MeHex-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-D-Etg-Val)

Experimental procedures as described in Examples 1-4 and 6-7, starting with 200 mg of resin, were carried out with the only exception that, in Example 4, Fmoc-Thr-OH was replaced by Fmoc-D-Etg-OH. The product was characterized by HPLC (t_(R) 17.0 min, Condition B) and MALDI-TOF-MS, calcd for C₇₅H₁₂₆N₁₄O₁₆, 1,479.0. Found: m/z 1,501.0 [M+Na]⁺, 1,517.9 [M+K]⁺.

Example 20c 5-MeHex-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-D-Thr-Val)

Experimental procedures as described in Examples 1-4 and 6-7, starting with 200 mg of resin, were carried out with the only exception that, in Example 4, Fmoc-Thr(tBu)-OH was replaced by Fmoc-D-Thr(tBu)-OH. The product was characterized by HPLC (t_(R) 19.9 min, Condition B) and MALDI-TOF-MS, calcd for C₇₅H₁₂₆N₁₄O₁₇, 1,494.9. Found: m/z 1,517.4 [M+Na]⁺, 1,533.4 [M+K]⁺.

Example 20d 5-MeHex-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-D-allo-Thr-Val)

Experimental procedures as described in Examples 1-4 and 6-7, starting with 200 mg of resin, were carried out with the only exception that, in Example 4, Fmoc-Thr(tBu)-OH was replaced by Fmoc-D-allo-Thr-OH. The product was characterized by HPLC (t_(R) 18.0 min, Condition B) and MALDI-TOF-MS, calcd for C₇₅H₁₂₆N₁₄O₁₇, 1,494.9. Found: m/z 1,496.6 [M+H]⁺, 1,518.6 [M+Na]⁺, 1,534.6 [M+K]⁺.

Example 20e 5-MeHex-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-D-Phe-Val)

Experimental procedures as described in Examples 1-7, starting with 200 mg of resin, were carried out with the only exception that, in Example 4, Fmoc-Thr-OH was replaced by Fmoc-D/L-(b-OH)Phe-OH. The product was characterized by HPLC (t_(R) 22.2 min, Condition B) and MALDI-TOF-MS, calcd for C₈₀H₁₂₆N₁₄O₁₆, 1,538.95. Found: m/z 1,540.3 [M+H]⁺, 1,562.4 [M+Na]⁺, 1,578.3 [M+K]⁺.

Example 21 5-MeHex-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-Dpa-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures as described in Examples 1-7, starting with 200 mg of resin, were carried out with the only exceptions that, in Example 2, Fmoc-D-allo-Thr-OH was replaced by Fmoc-D-Dpa(Alloc)-OH and that before the incorporation of Alloc-Val-OH, which was incorporated as the rest of protected amino acids, the Alloc group from the Dpa was removed as indicated above. The product was characterized by HPLC and ESMS, calcd for C₇₄H₁₂₃N₁₅O₁₅, 1,461.9. Found: m/z 1,463.3 [M+H]⁺.

Example 22 But-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures as described in Examples 1-7, starting with 200 mg of resin, were carried out with the only exceptions that, in Example 3, 5-MeHex was replaced by But-OH. The product was characterized by HPLC (t_(R) 14.7 min, Condition B) and MALDI-TOF-MS, calcd for C₇₂H₁₁₈ N₁₄O₁₆, 1,435.9. Found: m/z 1,459.6 [M+Na]⁺, 1,475.6 [M+K]⁺.

Example 22bis But-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-Val-Phe-Z-Dhb-Val)

Obtained as a side product during the preparation (racemization during the cyclization step) of Example 22. The product was characterized by HPLC (t_(R) 16.0 min, Condition B) and MALDI-TOF-MS, calcd for C₇₂H₁₁₈N₁₄O₁₆, 1,435.9. Found: m/z 1,459.5 [M+Na]⁺, 1,475.5 [M+K]⁺.

Example 23 3-MeBut-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures as described in Examples 1-7, starting with 200 mg of resin, were carried out with the only exceptions that, in Example 3, 5-MeHex was replaced by 3-MeBut-OH. The product was characterized by HPLC (t_(R) 15.9 min, Condition B) and MALDI-TOF-MS, calcd for C₇₃H₁₂₀N₁₄O₁₆, 1,449.9. Found: m/z 1,473.2 [M+Na]⁺, 1,489.2 [M+K]⁺.

Example 23bis 3-MeBut-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Obtained as a side product during the preparation (racemization during the cyclization step) of Example 23. The product was characterized by HPLC (t_(R) 17.0 min, Condition B) and ESMS, calcd for C₇₃H₁₂₀N₁₄O₁₆, 1,449.9. Found: m/z 1,473.3 [M+Na]⁺, 1,489.4 [M+K]⁺.

Example 24 3,3-DiMeBut-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures as described in Examples 1-7, starting with 200 mg of resin, were carried out with the only exceptions that, in Example 3, 5-MeHex was replaced by 3,3-DiMeBut-OH. The product was characterized by HPLC (t_(R) 16.3 min, Condition B) and MALDI-TOF-MS, calcd for C₇₄H₁₂₂N₁₄O₁₆, 1,463.9. Found: m/z 1,487.4 [M+Na]⁺, 1,503.6 [M+K]⁺.

Example 24bis 3,3-DiMeBut-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-Val-Phe-Z-Dhb-Val)

Obtained as a side product during the preparation (racemization during the cyclization step) of Example 24. The product was characterized by HPLC (t_(R) 17.6 min, Condition B) and MALDI-TOF-MS, calcd for C₇₄H₁₂₂N₁₄O₁₆, 1,463.9. Found: m/z 1,487.3 [M+Na]⁺, 1,503.3 [M+K]⁺.

Example 25 4-MePen-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures as described in Examples 1-7, starting with 200 mg of resin, were carried out with the only exceptions that, in Example 3, 5-MeHex was replaced by 4-MePen-OH. The product was characterized by HPLC (t_(R) 16.5 min, Condition B) and MALDI-TOF-MS, calcd for C₇₄H₁₂₂N₁₄O₁₆, 1,463.9. Found: m/z 1,487.7 [M+Na]⁺, 1,503.6 [M+K]⁺.

Example 25bis 4-MePen-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-Val-Phe-Z-Dhb-Val)

Obtained as a side product during the preparation (racemization during the cyclization step) of Example 25. The product was characterized by HPLC (t_(R) 17.8 min, Condition B) and MALDI-TOF-MS, calcd for C₇₄H₁₂₂N₁₄O₁₆, 1,463.9. Found: m/z 1,487.8 [M+Na]⁺, 1,503.6 [M+K]⁺.

Example 26 Hep-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures as described in Examples 1-7, starting with 200 mg of resin, were carried out with the only exceptions that, in Example 3, 5-MeHex was replaced by Hep-OH. The product was characterized by HPLC (t_(R) 17.5 min, Condition B) and MALDI-TOF-MS, calcd for C₇₅H₁₂₄N₁₄O₁₆, 1,477.9. Found: m/z 1,501.4 [M+Na]⁺, 1,517.5 [M+K]⁺.

Example 26bis Hep-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-Val-Phe-Z-Dhb-Val)

Obtained as a side product during the preparation (racemization during the cyclization step) of Example 26. The product was characterized by HPLC (t_(R) 18.9 min, Condition B) and MALDI-TOF-MS, calcd for C₇₅H₁₂₄N₁₄O₁₆, 1,477.9. Found: m/z 1,501.6 [M+Na]⁺, 1,517.7 [M+K]⁺.

Example 27 Pal-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures as described in Examples 1-7, starting with 200 mg of resin, were carried out with the only exceptions that, in Example 3, 5-MeHex was replaced by Pal-OH. The product was characterized by HPLC (t_(R) 22.1 min, Condition G) and MALDI-TOF-MS, calcd for C₈₄H₁₄₂N₁₄O₁₆, 1,603.1. Found: m/z 1,626.9 [M+Na]⁺, 1,642.9 [M+K]⁺.

Example 27bis Pal-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-Val-Phe-Z-Dhb-Val)

Obtained as a side product during the preparation (racemization during the cyclization step) of Example 27. The product was characterized by HPLC (t_(R) 23.2 min, Condition G) and MALDI-TOF-MS, calcd for C₈₄H₁₄₂N₁₄O₁₆, 1,603.1. Found: m/z 1,626.8 [M+Na]⁺, 1,642.8 [M+K]⁺.

Example 27a 4-DiMeABut-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures as described in Examples 1-7, starting with 200 mg of resin, were carried out with the only exceptions that, in Example 3, 5-MeHex was replaced by 4-DiMeABut-OH. The product was characterized by HPLC (t_(R) 12.0 min, Condition B) and MALDI-TOF-MS, calcd for C₇₄H₁₂₃N₁₅O₁₆, 1,477.9. Found: m/z 1,478.6 [M+H]⁺, 1,500.6 [M+Na]⁺, 1,516.6 [M+K]⁺.

Example 27b 2-Hedo-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures as described in Examples 1-7, starting with 200 mg of resin, were carried out with the only exceptions that, in Example 3, 5-MeHex was replaced by 2-Hedo-OH. The product was characterized by HPLC (t_(R) 15.8 min, Condition B) and MALDI-TOF-MS, calcd for C₇₄H₁₁₈N₁₄O₁₆, 1,458.9. Found: m/z 1,460.0 [M+H]⁺, 1,482.0 [M+Na]⁺, 1,497.9 [M+K]⁺.

Example 27c 4-AcBut-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures as described in Examples 1-7, starting with 200 mg of resin, were carried out with the only exceptions that, in Example 3, 5-MeHex was replaced by 4-AcBut-OH. The product was characterized by HPLC (t_(R) 18.2 min, Condition B) and MALDI-TOF-MS, calcd for C₇₄H₁₂₀N₁₄O₁₈, 1,492.9. Found: m/z 1,493.7 [M+H]⁺, 1,515.8 [M+Na]⁺, 1,531.7 [M+K]⁺.

Example 27d 4-HOBut-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures as described in Examples 1-7, starting with 200 mg of resin, were carried out with the only exceptions that, in Example 3, 5-MeHex was replaced by 4-HOBut-OH. The product was characterized by HPLC (t_(R) 16.6 min, Condition B) and MALDI-TOF-MS, calcd for C₇₂H₁₁₈N₁₄O₁₇, 1,450.9. Found: m/z 1,451.6 [M+H]⁺, 1,473.6 [M+Na]⁺, 1,489.6 [M+K]⁺.

Example 27e Ac-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures as described in Examples 1-7, starting with 200 mg of resin, were carried out with the only exceptions that, in Example 3, 5-MeHex was replaced by HOAc. The product was characterized by HPLC (t_(R) 17.0 min, Condition B) and MALDI-TOF-MS, calcd for C₇₀H₁₁₄N₁₄O₁₆, 1,406.9. Found: m/z 1,407.8 [M+H]⁺, 1,429.8 [M+Na]⁺.

Example 27f TFA-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Obtained as a side product during the preparation (trifluoroacetylion during the cyclization step) of Example 27e. The product was characterized by HPLC (t_(R) 14.7 min, Condition B) and MALDI-TOF-MS, calcd for C₇₀H₁₁₁F₃N₁₄O₁₆, 1,460.8. Found: m/z 1,462.0 [M+H]⁺, 1,484.1 [M+Na]⁺, 1,500.0 [M+K]⁺.

Example 27g AcButBut-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures as described in Examples 1-7, starting with 200 mg of resin, were carried out with the only exceptions that, in Example 3, 5-MeHex was replaced by AcButBut-OH. The product was characterized by HPLC (t_(R) 14.1 min, Condition B) and MALDI-TOF-MS, calcd for C₇₈H₁₂₆N₁₄O₂₀, 1,578.9. Found: m/z 1,581.2 [M+H]⁺, 1,602.2 [M+Na]⁺, 1,618.2 [M+K]⁺.

Example 27h IBut-D-allo-Ile-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures as described in Examples 1-7, starting with 200 mg of resin, were carried out with the only exceptions that, in Example 3, 5-MeHex was replaced by Fmoc-D-allo-Ile-OH, removal of the Fmoc group and acylation with IBut-OH. The product was characterized by HPLC (t_(R) 15.3 min, Condition B) and MALDI-TOF-MS, calcd for C₇₈H₁₂₉N₁₅O₁₇, 1,548.0. Found: m/z 1,548.8 [M+H]⁺, 1,570.8 [M+Na]⁺, 1,586.8 [M+K]⁺.

Example 27i Lit-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures as described in Examples 1-7, starting with 200 mg of resin, were carried out with the only exceptions that, in Example 3, 5-MeHex was replaced by Lit-OH. The product was characterized by HPLC (t_(R) 13.1 min, Condition H) and MALDI-TOF-MS, calcd for C₉₂H₁₅₀N₁₄O₁₇, 1,723.1. Found: m/z 1,724.6 [M+H]⁺, 1,746.6 [M+Na]⁺, 1,761.5 [M+K]⁺.

Example 27j TFA-Lit-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Obtained as a side product during the preparation (trifluoroacetylion during the cyclization step) of Example 27i. The product was characterized by HPLC (t_(R) 17.1 min, Condition H) and MALDI-TOF-MS, calcd for C₉₄H₁₅₉F₃N₁₄O₁₈, 1,819.1. Found: m/z 1,820.6 [M+H]⁺, 1,842.6 [M+Na]⁺, 1,858.6 [M+K]⁺.

Example 27k TIco-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures as described in Examples 1-7, starting with 200 mg of resin, were carried out with the only exceptions that, in Example 3, 5-MeHex was replaced by TIco-OH. The product was characterized by HPLC (t_(R) 16.8 min, Condition H) and ES-MS, calcd for C₉₂H₁₅₈N₁₄O₁₆, 1,715.2. Found: m/z 858.2 [M+H]+/2, 1,171.8 [M+H]⁺.

Example 28 H-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures as described in Examples 1-7, starting with 200 mg of resin, were carried out with the only exceptions that, in Example 3, 5-MeHex was not incorporated and Fmoc-D-Val-OH was replaced by Fmoc-D-Val-OH. The product was characterized by HPLC (t_(R) 11.6 min, Condition B) and MALDI-TOF-MS, calcd for C₆₈H₁₁₂N₁₄O₁₅, 1,364.8. Found: m/z 1,388.3 [M+Na]⁺, 1,404.3 [M+K]⁺.

Example 28bis H-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-Val-Phe-Z-Dhb-Val)

Obtained as a side product during the preparation (racemization during the cyclization step) of Example 28. The product was characterized by HPLC (t_(R) 12.9 min, Condition B) and MALDI-TOF-MS, calcd for C₆₈H₁₁₂N₁₄O₁₅, 1,364.8. Found: m/z 1,388.4 [M+Na]⁺, 1,404.4 [M+K]⁺.

Example 29 5-MeHex-D-Val-Thr-Val-D-Val-D-Pro-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures essentially as described in Examples 1-7, but according to the scheme 2.

The synthesis starts with 200 mg of resin and Fmoc-Orn(Boc)-OH was not incorporated. The product was characterized by HPLC (t_(R) 23.9 min, Condition A) and MALDI-TOF-MS, calcd for C₇₀H₁₁₄N₁₂O₁₅, 1,362.9. Found: m/z 1,386.4 [M+Na]⁺. 1,402.4 [M+K]⁺.

Example 29bis 5-MeHex-D-Val-Thr-Val-D-Val-D-Pro-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Obtained as a side product during the preparation (racemization during the cyclization step) of Example 29. The product was characterized by HPLC and MALDI-TOF-MS.

Example 30 5-MeHex-D-Val-Thr-Val-D-Val-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures essentially as described in Examples 1-7, but according the scheme 2. The synthesis starts with 200 mg of resin and Fmoc-Orn(Boc)-OH and Fmoc-D-Pro-OH were not incorporated. The product was characterized by HPLC (t_(R) 20.3 min, Condition B) and MALDI-TOF-MS, calcd for C₆₅H₁₀₇N₁₁O₁₄, 1,265.8. Found: m/z 1,288.5 [M+Na]⁺, 1,304.5 [M+K]⁺.

Example 31 5-MeHex-D-Val-Thr-Val-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z Dhb-Val)

Experimental procedures essentially as described in Examples 1-7, but according the scheme 2. The synthesis starts with 200 mg of resin and Fmoc-Orn(Boc)-OH, Fmoc-D-Pro-OH, and Fmoc-D-Val-OH were not incorporated. The product was characterized by HPLC (t_(R) 20.0 min, Condition B) and MALDI-TOF-MS, calcd for C₆₀H₉₈N₁₀O₁₃, 1,166.7. Found: m/z 1,190.9 [M+Na]⁺, 1,206.9 [M+K]⁺.

Example 32 5-MeHex-D-Val-Thr-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures essentially as described in Examples 1-7, but according the scheme 2. The synthesis starts with 200 mg of resin and Fmoc-Orn(Boc)-OH, Fmoc-D-Pro-OH, Fmoc-D-Val-OH, and Fmoc-Val-OH were not incorporated. The product was characterized by HPLC (t_(R) 24.6 min, Condition A) and MALDI-TOF-MS, calcd for C₅₅H₈₉N₉O₁₂, 1,067.7. Found: m/z 1,068.7 [M+H]⁺, 1,090.6 [M+Na]⁺, 1,106.5[M+K]⁺.

Example 33 5-MeHex-D-Val-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures essentially as described in Examples 1-7, but according the scheme 2. The synthesis starts with 200 mg of resin and Fmoc-Orn(Boc)-OH, Fmoc-D-Pro-OH, Fmoc-D-Val-OH, Fmoc-Val-OH, and Fmoc-Thr(tBu)-OH were not incorporated. The product was characterized by HPLC (t_(R) 19.8 min, Condition B) and MALDI-TOF-MS, calcd for C₅₁H₈₂N₈O₁₀, 966.6. Found: m/z 990.7 [M+Na]⁺, 1007.2 [M+K]⁺.

Example 34 5-MeHex-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures essentially as described in Examples 1-7, but according the scheme 2. The synthesis starts with 200 mg of resin and Fmoc-Orn(Boc)-OH, Fmoc-D-Pro-OH, Fmoc-D-Val-OH, Fmoc-Val-OH, Fmoc-Thr(tBu)-OH, and Fmoc-D-Val-OH were not incorporated. The product was characterized by HPLC (t_(R) 22.0 min, Condition B) and MALDI-TOF-MS, calcd for C₄₆H₇₃N₇O₉, 867.6. Found: m/z 890.6 [M+Na]⁺, 906.6 [M+K]⁺.

Example 35 5-MeHex-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val)

Experimental procedures essentially as described in Examples 1-7, but according the scheme 2. The synthesis starts with 200 mg of resin and Fmoc-D-allo-Ile-OH, Fmoc-Orn(Boc)-OH, Fmoc-D-Pro-OH, Fmoc-D-Val-OH, Fmoc-Val-OH, Fmoc-Thr(tBu)-OH, and Fmoc-D-Val-OH were not incorporated. The product was characterized by HPLC (t_(R) 17.1 min, Condition B) and ESMS, calcd for C₄₀H₆₂N₆O₈, 754.5 Found: m/z 755.7 [M+H]⁺, 777.7 [M+Na]⁺, 793.7 [M+K]⁺.

Bioactivity

The bioactivity of compounds of this invention is demonstrated by the results in the following tables obtained in accordance with the methodology of Beijeron et al., Biochem and Bioph Res. Comm., 1984, 121, 3, 848-854. The cell lines are P388, murine lymphoma; A549, human lung carcinoma; HT-29, human colon carcinoma; MEL-28, human melanoma; DU-145, human prostate carcinoma.

TABLE Kahalalide F congeners Compound Cycle Chain** MW 27j cyclo(D-allo-Thr-D-allo-Ile-D- Terminal: TFA-Lit- 1820 Val-Phe-Z-Dhb-Val) 27i cyclo(D-allo-Thr-D-allo-Ile-D- Terminal: lithocholoyl (Lit). 1724 Val-Phe-Z-Dhb-Val) 27 cyclo(D-allo-Thr-D-allo-Ile-D- Terminal: palmitoyl Palm 1604 Val-Phe-Z-Dhb-Val) 27 bis cyclo(D-allo-Thr-D-allo-Ile-Val- Terminal: palmitoyl Palm 1604 Phe-Z-Dhb-Val) 27g cyclo(D-allo-Thr-D-allo-Ile-D- Terminal: 4-(4- 1579 Val-Phe-Z-Dhb-Val) acetoxybutanoyloxy)-butyryl (AcButBut-) 27h cyclo(D-allo-Thr-D-allo-Ile-D- IBut-D-allo-Ile-D-Val-L-Thr-L-Val- 1548 Val-Phe-Z-Dhb-Val) D-Val-D-Pro-L-Orn-D-allo-Ile- 20e cyclo(D-allo-Thr-D-allo-Ile-D- 5-MeHex-D-Val-L-Thr-L-Val-D- 1539 Val-Phe-D-Phe-Val)- Val-D-Pro-L-Orn-D-allo-Ile- D-Phe: a,b-didehydro- phenylalanine 20c cyclo(D-allo-Thr-D-allo-Ile-D- 5-MeHex-D-Val-L-Thr-L-Val-D- 1495 Val-Phe-Thr-Val) Val-D-Pro-L-Orn-D-allo-Ile- 27c cyclo(D-allo-Thr-D-allo-Ile-D- Terminal: 4-acetoxibutyryl 1493 Val-Phe-Z-Dhb-Val) (4-AcBut) 20 cyclo(D-allo-Thr-D-allo-Ile-D- 5-MeHex-D-Val-L-Thr-L-Val-D- 1479 Val-Phe-L-Etg-Val) Val-D-Pro-L-Orn-D-allo-Ile- 20b cyclo(D-allo-Thr-D-allo-Ile-D- 5-MeHex-D-Val-L-Thr-L-Val-D- 1479 Val-Phe-D-Etg-Val) Val-D-Pro-L-Orn-D-allo-Ile- 27a cyclo(D-allo-Thr-D-allo-Ile-D- Terminal: N,N-dimethyl-4- 1478 Val-Phe-Z-Dhb-Val) aminobutyryl (4-DiMeABut) (as Scheuer) cyclo(D-allo-Thr-D-allo-Ile-D- 5-MeHex-D-Val-L-Thr-D-Val-L- 1477 15 Val-Phe-Z-Dhb-Val) Val-D-Pro-L-Orn-D-allo-Ile- 15 bis cyclo(D-allo-Thr-D-allo-Ile-Val- 5-MeHex-D-Val-L-Thr-D-Val-L- 1477 Phe-Z-Dhb-Val) Val-D-Pro-L-Orn-D-allo-Ile- 26 cyclo(D-allo-Thr-D-allo-Ile-D- Terminal: Heptanoyl (Hep) 1477 Val-Phe-Z-Dhb-Val) 26 bis cyclo(D-allo-Thr-D-allo-Ile-Val- Terminal: Heptanoyl (Hep) 1477 Phe-Z-Dhb-Val) (Rinehart) 7 cyclo(D-allo-Thr-D-allo-Ile-D- 5-MeHex-D-Val-L-Thr-L-Val-D- 1477 Val-Phe-Z-Dhb-Val) Val-D-Pro-L-Orn-D-allo-Ile-  7 bis cyclo(D-allo-Thr-D-allo-Ile-Val- 5-MeHex-D-Val-L-Thr-L-Val-D- 1477 Phe-Z-Dhb-Val) Val-D-Pro-L-Orn-D-allo-Ile- 24 cyclo(D-allo-Thr-D-allo-Ile-D- Terminal: 3,3-dimethylbutyryl 1463 Val-Phe-Z-Dhb-Val) (3,3-DiMeBut) 24 bis cyclo(D-allo-Thr-D-allo-Ile-Val- Terminal: 3,3-dimethylbutyryl 1463 Phe-Z-Dhb-Val) (3,3-DiMeBut) 25 cyclo(D-allo-Thr-D-allo-Ile-D- Terminal: 3-Methylpentanoyl 1463 Val-Phe-Z-Dhb-Val) (4-MePen) 25 bis cyclo(D-allo-Thr-D-allo-Ile-Val- Terminal: 3-Methylpentanoyl 1463 Phe-Z-Dhb-Val) (4-MePen) 27f cyclo(D-allo-Thr-D-allo-Ile-D- Terminal: trifluoracetyl (TFA) 1461 Val-Phe-Z-Dhb-Val) 27b cyclo(D-allo-Thr-D-allo-Ile-D- Terminal: 2,4-hexadienoyl (Hedo) 1459 Val-Phe-Z-Dhb-Val) 27d cyclo(D-allo-Thr-D-allo-Ile-D- Terminal: 4-hydroxybutyryl 1451 Val-Phe-Z-Dhb-Val) 23 cyclo(D-allo-Thr-D-allo-Ile-D- Terminal: 3-Methylbutyryl 1451 Val-Phe-Z-Dhb-Val) (3-MetBut) 23b cyclo(D-allo-Thr-D-allo-Ile-Val- Terminal: 3-Methylbutyryl 1451 Phe-Z-Dhb-Val) (3-MetBut) 22 cyclo(D-allo-Thr-D-allo-Ile-D- Terminal: Butyryl (But) 1435 Val-Phe-Z-Dhb-Val) 22b cyclo(D-allo-Thr-D-allo-Ile-Val- Terminal: Butyryl 1435 Phe-Z-Dhb-Val) 27c cyclo(D-allo-Thr-D-allo-Ile-D- Terminal: acetyl 1407 Val-Phe-Z-Dhb-Val) 28 cyclo(D-allo-Thr-D-allo-Ile-D- Terminal: no fatty acid 1365 Val-Phe-Z-Dhb-Val) 28 bis cyclo(D-allo-Thr-D-allo-Ile-Val- Terminal: no fatty acid 1365 Phe-Z-Dhb-Val) 29 cyclo(D-allo-Thr-D-allo-Ile-D- 5-MeHex-D-Val-L-Thr-L-Val-D- 1363 Val-Phe-Z-Dhb-Val) Val-D-Pro-D-allo-Ile- 29 bis cyclo(D-allo-Thr-D-allo-Ile-Val- 5-MeHex-D-Val-L-Thr-L-Val-D- 1363 Phe-Z-Dhb-Val) Val-D-Pro-D-allo-Ile- 31 cyclo(D-allo-Thr-D-allo-Ile-D- 5-MeHex-D-Val-L-Thr-L-Val-D- 1167 Val-Phe-Z-Dhb-Val) allo-Ile- 32 cyclo(D-allo-Thr-D-allo-Ile-D- 5-MeHex-D-Val-L-Thr-D-allo-Ile- 1068 Val-Phe-Z-Dhb-Val) 19 L-Phe-D-Leu-L-Pro-_-Thr-Gly- 5-MeHex-L-Tyr- 878 D-Ser 34 cyclo(D-allo-Thr-D-allo-Ile-D- 5-MeHex-D-allo-Ile 868 Val-Phe-Z-Dhb-Val) 35 cyclo(D-allo-Thr-D-allo-Ile-D- 5-MeHex- 754 Val-Phe-Z-Dhb-Val) **Compounds where the chain is indicated Terminal have the same chain as in compound 7, but with the indicated substitution for the 5-MeHex.

TABLE Cytotoxicity of Kahalalide F congeners IC50 (micromol) values for derivatives Compound A549M DU145M HT29M MEL28M p388M 27j 5.49E−05 5.49E−05 5.49E−05 5.49E−05 2.75E−03 27i 5.80E−04 5.80E−04 2.90E−05 1.45E−04 1.45E−03 27 1.56E−04 3.12E−05 6.23E−05 6.23E−05 3.12E−03 27bis >3.12E−03   1.56E−03 6.23E−04 6.23E−04 >3.12E−03   27g >6.33E−04   >6.33E−04   1.58E−03 3.17E−03 >3.17E−03   27h NA NA NA NA NA 20e 3.25E−03 6.50E−04 NA NA NA 20c NA NA NA NA NA 27c NA NA 6.70E−04 3.35E−03 NA 20 >3.38E−03   >3.38E−03   >3.38E−03   >3.38E−03   >3.38E−03   20b >3.38E−03   3.38E−03 3.38E−03 >3.38E−03   >3.38E−03   27a NA NA NA NA NA (as Scheuer) >3.39E−03   3.39E−03 3.39E−03 >3.39E−03   >3.39E−03   15 15 bis >3.39E−03   >3.39E−03   >3.39E−03   >3.39E−03   >3.39E−03   26 3.39E−04 3.39E−05 6.77E−04 1.69E−03 3.39E−03 26 bis >3.39E−03   >3.39E−03   3.39E−04 1.69E−03 >3.39E−03   (Rinehart) 3.39E−04 1.69E−04 3.39E−05 3.39E−04 >3.39E−03    7  7 bis >3.39E−03   >3.39E−03   >3.39E−03   >3.39E−03   >3.39E−03   24 1.71E−03 3.42E−04 3.42E−04 3.42E−03 >3.42E−03   24 bis >3.42E−03   >3.42E−03   3.42E−04 >3.42E−03   >3.42E−03   25 3.42E−04 3.42E−04 >3.42E−03   >3.42E−03   >3.42E−03   25 bis >3.42E−03   >3.42E−03   >3.42E−03   >3.42E−03   >3.42E−03   27f NA 3.42E−03 >3.42E−03   3.42E−03 3.42E−03 27b 3.43E−03 6.85E−04 3.43E−03 NA NA 27d NA NA NA NA NA 23 >3.45E−03   >3.45E−04   >3.45E−05   >3.45E−04   >3.45E−03   23b >3.45E−03   >3.45E−03   >3.45E−03   >3.45E−03   >3.45E−03   22 >3.48E−03   1.74E−03 NA NA NA 22b >3.48E−03   >3.48E−03   1.74E−03 >3.48E−03   >3.48E−03   27c NA >3.55E−03   >3.55E−03   >3.55E−03   >3.55E−03   28 >3.66E−03   >3.66E−03   >3.66E−03   >3.66E−03   >3.66E−03   28 bis >3.66E−03   >3.66E−03   NA NA NA 29 >3.67E−03   >3.67E−03   >3.67E−03   >3.67E−03   >3.67E−03   29 bis >3.67E−03   >3.67E−03   >367E−03   >3.67E−03   >3.67E−03   31 >4.28E−04   >4.28E−05   >4.28E−03   >4.28E−03   >4.28E−03   32 NA NA 4.68E−05 4.68E−05 >4.68E−03   19 >5.69E−03   >5.69E−03   NA NA NA 34 NA NA >5.76E−03   >5.76E−03   >5.76E−03   35 >5.76E−03   >5.76E−03   >5.76E−03   >5.76E−03   >5.76E−03  

-   Hamann, M. T.; Scheuer, P. J. J. Am. Chem. Soc., 1993. “Kahalalide     F: a Bioactive Depsipeptide from the Sacoglossan Mollusk Elysia     refescens and the Green Alga Bryopsis sp.”, vol. 115, pp. 5825-5826. -   Hamann, M. T., et al. J. Org. Chem., 1996. “Kahalalides: Bioactive     Peptides from Marine Mollusk Elysia rufescens and its Algal Diet     Bryopsis sp.”, vol. 61, pp. 6594-6660. -   García-Rocha, M., et al. Cancer Lett., 1996. “The Antitumoral     Compound Kahalalide F Acts on Cell Lysosomes”, vol. 99, pp. 43-50. -   Hamann, M. T., et al. J. Org. Chem., 1998. “Kahalalides: Bioactive     Peptides from Marine Mollusk Elysia rufescens and its Algal Diet     Bryopsis sp.”, vol. 63, p. 485 (Correction of J. Org. Chem., 1996,     vol. 61, pp. 6594-6660). -   Lloyd-Williams, P., et al. Chemical Approaches to the Synthesis of     Peptides and Proteins. CRC Press, Boca Raton (Fla.), 1997. -   Goetz, G., et al. J. Nat. Prod., 1997. “Two Acyclic Kahalalides from     the Sacoglossan Mollusk Elysia rufescens”, vol. 60, pp. 562-567. -   Goetz, G., et al. Tetrahedron, 1999. The Absolute Stereochemistry of     Kahalalide F”, vol. 55, pp. 7739-7746. -   Kan, Y., et al. J. Nat. Prod., 1999, vol. 62, pp. 1169-1172. -   Horgen, F. D. et al. J. Nat. Prod., 2000, vol. 63, pp. 152-154. 

1-10. (canceled)
 11. A compound having the following Formula II:

wherein R₇ is selected such that Aaa-7 is D-allo-Ile and R₈ is 5-MeHex-D-Val-Thr-Val-D-Val-D-Pro-Orn-; and further wherein R₁, R₃, R₄, R₅, and R₆ are each independently selected from hydrogen or an alkyl group, an aryl group, or an aralkyl group each optionally substituted with a hydroxy group, a mercapto group, an amino group, a guanidino group, or a halogen group; any of R₁, R₃, R₄, R₅, and R₆ can optionally replace the hydrogen on the α-nitrogen to form a proline ring; R₂ is selected from hydrogen, an alkyl group, and an aralkyl group; X₁ is selected from O, S, and N, with the proviso that when X₁ is O or S then R₂ is not present; X₂ is selected from an alkenyl group, an alkyl group, an aryl group, and an aralkyl group, each optionally substituted with a hydroxy group, a mercapto group, an amino group, a guanidino group, and a halogen group; and further wherein one or both Aaa-5 and Aaa-6 are optionally not present such that the remaining subunits form a ring, or an additional Aaa-7′ subunit is optionally inserted into the ring between Aaa-6 and Aaa-1, wherein Aaa-7′ is independently an amino acid; wherein said compound of Formula II is not 5-MeHex-D-Val-Thr-Val-D-Val-D-Pro-Orn-D-allo-Ile-cyclo(D-allo-Thr-D-allo-Ile-D-Val-Phe-Z-Dhb-Val).
 12. The compound according to claim 11, wherein Aaa-1 is D-allo-Thr.
 13. The compound according to claim 11, wherein Aaa-2 is D-allo-Ile.
 14. The compound according to claim 11, wherein Aaa-3 is D-Val.
 15. The compound according to claim 11, wherein Aaa-4 is Phe.
 16. The compound according to claim 11, wherein Aaa-5 is Z-Dhb.
 17. The compound according to claim 11, wherein Aaa-6 is Val.
 18. A composition comprising a compound according to claim 11 and a pharmaceutically acceptable carrier or diluent.
 19. A method of synthesizing a compound having the following Formula II:

wherein R₇ is selected such that Aaa-7 is D-allo-Ile and R₈ is 5-MeHex-D-Val-Thr-Val-D-Val-D-Pro-Orn-; and further wherein R₁, R₃, R₄, R₅, and R₆ are each independently selected from hydrogen or an alkyl group, an aryl group, or an aralkyl group each optionally substituted with a hydroxy group, a mercapto group, an amino group, a guanidino group, or a halogen group; any of R₁, R₃, R₄, R₅, and R₆ can optionally replace the hydrogen on the α-nitrogen to form a proline ring; R₂ is selected from hydrogen, an alkyl group, and an aralkyl group; X₁ is selected from O, S, and N, with the proviso that when X₁ is O or S then R₂ is not present; X₂ is selected from an alkenyl group, an alkyl group, an aryl group, and an aralkyl group, each optionally substituted with a hydroxy group, a mercapto group, an amino group, a guanidino group, and a halogen group; and further wherein one or both Aaa-5 and Aaa-6 are optionally not present such that the remaining subunits form a ring, or an additional Aaa-7′ subunit is optionally inserted into the ring between Aaa-6 and Aaa-1, wherein Aaa-7′ is independently an amino acid; said method comprising a step of forming an amide bond between a carboxylic group and an amino group to accomplish a ring closure and form said cyclic portion, and wherein the starting material and product are optionally protected by one or more protecting groups, and wherein the carboxylic group participating in the amide bond formation and/or the amino group participating in the amide bond formation may optionally be protected or activated.
 20. The method according to claim 19, comprising a ring closure according to the following scheme:

wherein the starting material and product are optionally protected by one or more protecting groups, and wherein a carboxylic group of Aaa³ and/or an amino group of Aaa⁴ of the starting material may optionally be protected or activated.
 21. The method according to claim 19, wherein the amide bond forms between a carboxylic group of a D-Val and an amino group of a Phe.
 22. A method of treating cancer in a patient comprising administering a therapeutically-effective amount of a compound according to claim 11 to a patient in need thereof, wherein said cancer is selected from the group consisting of lung cancer, colon cancer, prostate cancer, lymphoma, and melanoma. 